Frequently Asked Questions

General Land Office Research

Department of Landscape Architecture

Iowa State University 

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Quotations from field notes or GLO Timeline or

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 Frequently Asked Questions

General Land Office
1. What was the General Land Office?
2. Why were GLO surveys done?
3. What was the deputy surveyor's job?
4. How were GLO surveys done?
5. Did deputy surveyors have help?

GLO notes

6. What happened to the field notes that GLO surveyors wrote?
7. What did the surveyors describe in their field notes?
8. Did the surveyors describe any features away from section lines?

GLO maps

9. What do the maps show?
10. What happened to the township maps?
ISU's GLO project
11. What ISU activities involve GLO data?
12. What GLO data are available?
13. What digital GLO data are available?
14. What do the digital historic vegetation map files contain?
15. What procedures were used to digitize the historic vegetation map data?
16. What do the digital field note files contain?
17. What procedure was used to digitize the field notes?
18. What GIS research has been conducted with the digital data?
19. Are there opportunities for additional research?
20. How can I get more information about the research?

Data limitations

21. How accurate were the GLO surveys?
22. How accurate are the digital GLO data?

General Land Office

1. What was the General Land Office?

The US General Land Office (GLO) was a part of the Federal government. Its main responsibility was to survey land in the central and western United States so that the land could be sold to settlers moving in to the area. Surveying the land made it easier to locate and legally describe the parcels purchased by settlers.

Under the Ordinance of 1785, the United States Public Land Survey (USPLS) system was established with the Geographer of the United States as the director. This began the system of subdividing land areas into regular parcels so that it could be sold to provide income for the Federal treasury. The Act of May 18, 1796 appointed a Surveyor General, who was given the power to deputize surveyors to carry out their duties. The Act of April 25, 1812 established the General Land Office within the Department of the Treasury. In 1849, the General Land Office into the newly-created Department of the Interior. In 1946, it became part of the new Bureau of Land Management (BLM).  These events and others are included in a GLO Timeline.

The Public Land Survey required meticulous work by a large number of people laboring under unfavorable working conditions. What began as a way for the new Federal government to make money, turned into quite a vast undertaking. For more information about the history of the GLO, see Surveys and Surveyors of the Public Domain 1785-1975 (U.S. Department of the Interior, Washington, D.C.) by Lola Cazier (1977).

2. Why were GLO surveys done?

GLO surveys were completed to aid the Federal government in "disposal" of land. In Iowa, "disposal" involved either selling land to Euro-American settlers or giving land to states, counties, schools, war veterans, railroads, steamboat companies, and others as rewards or economic incentives. According to Leland Sage in A History of Iowa (1974, p. 70), approximately 40 percent of the land was given in military bounties, 34 percent was sold for cash, and 12 percent was state grants for railroad construction. Here’s the complete list:

Percent    Purpose
39.7    Military bounties
33.7    Cash sales
11.7    State grants for railroad construction
4.9    State grants for education
3.4    State grants for swamp and saline lands
3.2    State grants for river improvements and public buildings
2.5    Homesteads
0.7    Agricultural college scrip locations
0.1    Timber claims
0.1    Miscellaneous
100.0    TOTAL

The GLO conducted the original public land survey of Iowa from 1832 to 1859. However, a few townships were resurveyed after 1859. Approximately 187 deputy surveyors in Iowa surveyed the section lines (township subdivisions) within the state's approximately 1650 townships. One-quarter of the state was completed by 1843, one-half was completed by 1848, three-quarters was completed by 1851, and by 1858, all but 275,000 acres had been surveyed. These 275,000 acres (primarily along the Missouri River) were finished by 1910.

3. What was the deputy surveyor's job?

The primary job of the deputy surveyors was to measure distances and mark the corners of each section.

Deputy surveyors were also required to document their surveys by writing notes and drawing maps in their field books. As they surveyed each section line, they recorded distances and significant features along the way. The majority of the notes document the surveyors’ task of measuring, locating, and constructing survey monuments at section corners and quarter-section corners.

Deputy surveyors were also required to describe "the face of the country." Their notes and maps briefly described the land and its natural resources (vegetation, water, soil, landform, and so on) at the time of the survey. The survey maps and notes produced by the GLO surveyors are among the few detailed, systematic data sources about Iowa before much of it was changed to a landscape of intensive agriculture.

4. How were GLO surveys done?

The GLO survey was a rectangular survey, rather than a boundary (metes and bounds) survey.   In Surveys and Surveyors of the Public Domain 1785-1975 (U.S. Department of the Interior, Washington, D.C.), Lola Cazier (1977, p. 17) said that by using the rectangular survey method, "the United States, for the most part, avoided the disputes, litigation, and bloodshed inherent in a metes and bounds system."  There were three major steps in completing the GLO rectangular survey.

Step 1 was to survey base lines and principal meridians on which all other surveying measurements were based. The GLO survey in Iowa is based on the 5th Principal Meridian (a north-south line at 91 degrees, 03 minutes, 42 seconds west longitude). The 5th Principal Meridian was adopted in 1815 and runs through eastern Iowa in the vicinity of Muscatine. The 5th Principal Meridian intersects its base line in east-central Arkansas (this east-west line is at 34 degrees, 44 minutes, 00 seconds north latitude).

Step 2 was to survey township lines. Township lines were surveyed at six-mile intervals and subdivided Iowa into townships that are approximately 36 square miles each. Each row (tier) of townships is numbered 65 through 100. Each column (range) of townships is numbered 7 East through 49 West. This produces a coordinate system used to number each survey township by tier and range. For example, the state capitol building in Des Moines is located in Tier 78 North, Range 24 West, 5th Principal Meridian. By the way, the word "township" has several different meanings, causing some confusion. These GLO survey (Congressional) townships are different than civil (political) townships, although in Iowa approximately 1,158 (70 percent) of the 1,657 civil townships follow Congressional township lines.

Step 3 was to subdivide townships into sections. Section lines were surveyed at one-mile intervals, creating sections that are approximately one mile square. Most sections cover an area of approximately 640 acres, although there are many sections that have a smaller or larger area due to survey correction lines, major rivers, state boundaries, or surveying errors.  Monuments or other marks were made at half-mile intervals, to later aid in subdividing the sections into quarter sections of approximately 160 acres.  Most of the land parcels originally purchased were aliquot parts of a section (even multiples of 40 acres), although due to size variation of some sections, fractional parts or lots were sometimes purchased.

5. Did deputy surveyors have help?

Yes. Each deputy surveyor was accompanied by several others. Each "survey party" typically consisted of the deputy surveyor, two chainmen, a flagman, and a marker (axeman). Sometimes one or two mound builders were added to the survey party. The deputy surveyor operated the compass (a surveying instrument on a tripod). The two chainmen dragged a 66-foot Gunter's chain along each section line to measure distances. The flagman marked the endpoint of the Gunter's chain each time it was put in position by the chainmen. The axeman and mound builders were responsible for blazing witness trees and bearing trees, erecting posts, digging pits, and building mounds to mark the section corners.

During the Iowa GLO survey, survey parties were typically paid $2.75 per mile surveyed. This amount was split among all members of the survey party. Typically, each member was paid $15 per month plus their keep. One deputy surveyor said that they could make "good money" if the weather was optimal (often it wasn't). Survey parties were responsible for their own equipment, food, and other supplies. Surveying section lines within a township typically took 5 to 15 days. Surveying 60 miles of section lines required about 120 miles of walking.  (East-west lines were surveyed twice ("over and back") and section lines were always surveyed from south to north (not a zig-zag pattern), that required walking from the north edge of the township to the south edge five times per township.)

You can see why deputy surveyors needed help. Surveying up and down slopes, through prairie, wetlands, rivers, and woodlands was difficult. Other obstacles included weather, hauling supplies, finding food and fresh water, primitive surveying technology, limited technical training, equipment problems, labor problems, preemptors (squatters), hostiles (Native Americans), military maneuvers, snake pits, and the dreaded mosquitoes.

For more information about GLO surveying methods in Iowa, see Original Instructions Governing Public Land Surveys of Iowa (Iowa Engineering Society, Ames) by J.S. Dodds (1943) and Public Land Surveys: History, Instructions, Methods (Collegiate Press, Ames) by Lowell O. Stewart (1935).


GLO notes

6. What happened to the field notes that GLO surveyors wrote?

GLO surveyors wrote their survey notes by hand in leather-bound field books. After the surveyors finished surveying a township and wanted to get paid, they returned their field books to the Surveyor General, whose office was in Dubuque.  (It was moved there from Cincinnati a few years after the Iowa survey began.)  The Surveyor General hired professional copyists, who made copies of the field notes by hand (manuscript copies). In the late 1930s (circa 1938), the Secretary of State hired typists to read the manuscript copies and type the GLO notes using manual typewriters. These typescript copies are stored in the library of the State Historical Society of Iowa in Des Moines and were microfilmed in the 1970s.

7. What did the surveyors describe in their field notes?

For each mile of section line, deputy surveyors were required to write distances (in chains and links) between section corners and quarter corners. Along the section lines, they also noted distances from section corners to landscape features (such as streams, escarpments, rock outcrops, line trees, and timber stands) and cultural features (such as cabins, fields, and trails). Sometimes, width or other dimensions of the features were recorded in the field notes. At section corners, surveyors listed the common name, distance and direction to at least two witness or bearing trees (if there were any within a reasonable distance). For each mile of section line, surveyors summarized the predominant vegetation and rated the soils (first rate, second rate, or third rate).

instructions1840b.jpg (64917 bytes)instructions1840a.jpg (59834 bytes)For each township, deputy surveyors were required to write a general description of the township's natural and cultural characteristics. This general description was usually one paragraph in length. It often included the surveyor's assessment of land use suitability for agriculture, mining, forestry, milling, or other use of interest to settlers moving in from the eastern states. Item 20 of the 1855 General Instructions to Deputy Surveyors required this description: "Besides the ordinary notes taken on line, (and which must always be written down on the spot, leaving nothing to be supplied by memory,) the deputy will subjoin, at the conclusion of his book, such further description or information touching any matter or thing connected with the township, (or other survey), which he may be able to afford, and may deem useful or necessary to be known- with a general description of the township in the aggregate, as respects the face of the country, its soil and geological features, timber, minerals, water, etc."

Deputy surveyors were required to follow printed instructions from the Surveyor General. During the Iowa survey, instructions were revised and printed in 1831, 1834, 1843, 1846, 1850, 1851, and 1855.  Instructions for the early years were quite brief and concentrated on surveying measurements.  Instructions for later years were more complete and explicit concerning descriptions of features in the landscape.

Excerpts from surveyors' field notes provide insight into their work and the landscape in which they worked. 

8. Did the surveyors describe any features away from section lines?

This didn't happen very often. The Surveyor General instructed deputy surveyors to survey offsets around major obstacles, such as a lake. This required that the surveyor establish a line parallel to the section line that would skirt the obstacle.

The Surveyor General also instructed deputy surveyors to survey rivers that were potentially navigable. This usually resulted in establishing a base line somewhat parallel to the river and measuring perpendicular lines to strategic points--usually meanders (bends in the river). Special data were recorded in the field books (a meander table) about these "meandered" rivers. In Iowa there are portions of 14 rivers that were meandered (considered by the GLO surveyors as potentially navigable).

Of course, there were places along the section lines where surveyors could see features off the section lines (section interiors). The areas seen depended on the topography, vegetation, weather conditions, and other factors (such as whether or not they were in a hurry).

Offsets, meanders, and observations away from the section lines were not common. Virtually all the data recorded by the deputy surveyors was limited to the section lines. For this reason, GLO surveys are considered transect surveys rather than area-wide surveys.


GLO maps

9. What do the maps show?

The Surveyor General required deputy surveyors to draw a map of the township, noting significant natural and cultural features. These features were sketched and labeled on a diagram sewn in the field book. The General Instructions of 1843 instructed deputy surveyors to "also make out and return with your original field notes an accurate plat or sketch of your surveys, which must exhibit the true situation of all objects noted in your field book." According to the Surveyor General's instructions of 1855, these maps were to contain "all the objects of topography on line necessary to illustrate the notes, viz: the distances on line at the crossings of streams, so far as such can be noted on the paper, and the direction of each by an arrowhead pointing downstream; also the intersection of line by prairies, marshes, swamps, ravines, ponds, lakes, hills, mountains, and all other matters indicated by the notes, to the fullest extent practicable."

Surveyors referred to these maps as "topographies." In Original Instructions Governing Public Land Surveys of Iowa (1943, p. 11), J.S. Dodds described topographies as "rather crude sketches and plots." In many cases, features were incompletely drawn because surveyors were limited to what they could measure and observe along section lines. Even though rivers, creeks, lakes, timber stands, valley bottoms, trails, and other extensive features may be completely drawn on the township maps, there are data points (measurements) only along section lines, resulting in a great deal of uncertainty about the features shown interior to the section lines.

10. What happened to the township maps?

Together, topographies and field notes were considered as the deputy surveyors’ "returns" to the Surveyor General. According to the National Archives, topographies were considered preliminary field maps rather than finished plat maps. Topographies were used as a guide (along with the field notes) to later draw refined maps at the Surveyor General's office in Dubuque. Official plat maps were drawn in triplicate at a scale of 2 inches per mile, using colored ink. After quality control inspection, these official plat maps contained the Surveyor General's statement and signature approving the plat as correct. Some of the plat map sheets include a meander table below the map.

One copy of each township plat map was originally kept at the Surveyor General's office in Dubuque, then transferred to the Secretary of State's office, then stored in the state archives of the State Historical Society of Iowa). A second copy ("headquarters plats") was originally sent to the General Land Office in Washington, D.C. and is now at the National Archives. A third copy was sent to the local land office and used as an aid to "disposing" of the land. After the local land office no longer needed their copy, it was returned to the General Land Office in Washington, D.C. and is now at the National Archives. These copies contain additional lines and annotations referring to specific parcels and landowners.


ISU's GLO project

11. What ISU activities involve GLO data?

Faculty and graduate students in animal ecology, anthropology, botany, civil engineering, forestry, history, landscape architecture, and other departments have used GLO notes and maps in their research on Iowa's past. Here are some examples:

In the 1930s, Lowell O. Stewart (Civil Engineering) described the history, instructions, and methods used in the rectangular system of surveying public lands. The book concentrates on technical aspects of surveying practice, particularly equipment, contract surveying system, and field techniques. See Public Land Surveys (Collegiate Press, Ames, Iowa) by Lowell O. Stewart (1935). [TA622 .St49p]

In the 1940s, J.S. Dodds (Civil Engineering) described the series of instructions by the GLO Surveyor General to deputy surveyors. This book was intended to inform contemporary surveyors who were involved in resurveying land that had been first surveyed by GLO surveyors. Particularly helpful are excerpts from correspondence, quotations from surveyors' field notes, and an index of deputy surveyors who worked in Iowa. See Original Instructions Governing Public Land Surveys of Iowa (Iowa Engineering Society, Ames, Iowa) by J.S. Dodds (1943).  [TA521 D661o]

In the 1950s, William Dick-Peddie (Botany) described characteristics of historic forest in Iowa based on GLO survey records. He studied species composition, size, and distribution in three study areas: (1) Allamakee, Jackson, and Lee Counties, (2) three east-west transects across the state, and (3) the valleys of the Des Moines River and Missouri River. See Presettlement Forest Types in Iowa (PhD dissertation, Department of Botany, Iowa State College, Ames) by William A. Dick-Peddie (1955). [QK484.I8 D561p]

In the 1970s, Paul Anderson (Landscape Architecture) compared distribution of historic vegetation from GLO township maps with interpretations of soil survey maps, aerial photographs, and historic atlas maps. See Vegetation Information in County Resource Planning (MLA Terminal Project, Department of Landscape Architecture, Iowa State University, Ames) by Paul F. Anderson (1974). [QK63 .A53x]

In the 1980s, George Thomson (Forestry) applied the line intercept transect method to estimate forest area in eight counties at the time of Euro-American settlement. Thomson used GLO township maps as the basis for his area estimates. Thomson then compared the estimated area with that from a 1935 study by state forester G.B. MacDonald. See Iowa's Forest Area in 1832: A Reevaluation (Proceedings of the Iowa Academy of Science 94(4): 116-120) by George W. Thomson (1987). [Q1 .Io8p]

In the 1980s, Donald Wall (Civil Engineering) summarized the historical events, Federal statutes, public land records for Iowa, and geodetic surveys in Iowa that relate to a comprehensive land information system. See Iowa land public records and geodetic surveys as a foundation for a land information system (MS thesis, Department of Civil and Construction Engineering, Iowa State University, Ames) by Donald K. Wall (1987). [ISU 1987 W154]

In the 1980s, Kathy Gourley (Anthropology) used GLO maps and notes to help document Native American sites in Iowa.  See Locations of Sauk, Mesquakie, and associated Euro-American sites 1832 to 1845 : an ethnohistoric approach (MA thesis, Department of Anthropology, Iowa State Univeristy, Ames) by Kathryn E. Gourley (1990). [ISU 1990 G744]

In the 1990s, Paul Anderson (Landscape Architecture and Agronomy) digitized GIS data containing 38 vegetation types from GLO township maps for all of Iowa. See GIS Research to Digitize Maps of Iowa 1832-1859 Vegetation from General Land Office Township Plat Maps (Iowa Department of Natural Resources, State Preserves Advisory Board, Des Moines; and Department of Landscape Architecture, Iowa State University, Ames) by Paul F. Anderson (1996). [QK63 G57x, 1997]

In the 1990s, Mike Miller, Jane Chen, and Said Musli (Landscape Architecture) developed GIS descriptive models of historic vegetation based on GLO maps and field notes. Miller and Musli developed qualitative and quantitative definitions of GLO vegetation types. Chen developed a hypermedia database linking GLO township maps and notes. See Analysis of historic vegetation patterns in Iowa using General Land Office surveys and a Geographic Information System by Michael C. Miller (1995), Development and demonstration of a hypermedia database for General Land Office surveyors’ field notes by Jane Chen (1998), and GIS descriptive modeling of General Land Office vegetation types in Hamilton County, Iowa by Said Musli (1999), MLA theses, Department of Landscape Architecture, Iowa State University, Ames. [ISU 1995 M56 / ISU 1998 C53 / ISU 1999 M87]

In the 2000s, Kathy Andersen (Animal Ecology) studied historical changes in several Iowa watersheds using GLO survey records, original drainage districts maps from the early 1900's, county atlases and other historical sources. These data were integrated into a GIS database and compared with modern features depicted on USGS topographical maps. See Historical alterations of surface hydrology in Iowa's small agricultural watersheds (MS thesis, Department of Animal Ecology, Iowa State University, Ames) by Katherine L. Andersen (2000). [ ISU 2000 A525]

In the 2000s, Patrick Brown and Steven Morgan (Landscape Architecture) used historic vegetation data from GLO records in GIS descriptive models comparing past landscape conditions to present conditions. Brown modeled contemporary and future habitats and compared them with historic habitats delineated by GLO maps. Morgan modeled contemporary and future land cover in a watershed, then compared surface runoff estimates with estimates of runoff under historic conditions. See Analysis of past and future urban growth impacts to habitat within Boone, Hamilton, Hardin, Marshall, Story and Webster counties in Iowa using FRAGSTATS and an urban growth model by Patrick D. Brown (2000) and Hydrologic modeling of overland flow within Little Beaver Creek watershed, Iowa by Steven R. Morgan (2001), MLA theses, Department of Landscape Architecture, Iowa State University, Ames. [ISU 2000 B75]

12. What GLO data are available?

Original GLO documents with township maps and field notes are stored in the National Archives and the archives of the State Historical Society of Iowa in Des Moines. Many of these documents, including the WPA typescript of the field notes, have been microfilmed. Copies of the microfilm may be purchased through Heritage Microfilm in Cedar Rapids.


13. What digital GLO data are available?

Two major categories of digital data are available through the ISU GLO project: maps and field notes.

Data from township maps for the entire state were digitized from 1992 to 1996. However, only vegetation polygons were digitized in this project. The project was supported by the Iowa Department of Natural Resources, State Preserves Board; and Iowa State University, Department of Landscape Architecture. The vegetation data were digitized for Geographic Information System (GIS) data analysis in landscape planning and management studies. In addition to digitizing maps, the research team developed a Microfilm Directory Database, researched historical GLO survey methods, and researched GIS modeling procedures to analyze vegetation character, quantity, and distribution from the vegetation map GIS files. Results of GIS spatial and statistical analysis are being used by land managers and researchers in understanding historic vegetation patterns, vegetation changes, and implications for vegetation preservation, restoration, and reconstruction.

These GLO historic vegetation data are in the form of Arc/Info coverages. These GIS files may be used with Arc/Info, ArcView, and other GIS software. Files are available through the Iowa Department of Natural Resources server Natural Resources Geographic Information System (NRGIS). Generalized map images of GLO historic vegetation are available through Iowa State University’s GLO GIS server.

Data from field notes for three counties have been digitized from 1996 to 2001. These counties include Dallas, Hamilton, and Polk. Field notes were digitized as part research projects by Paul Anderson and three graduate students in Landscape Architecture: Michael Miller, Jane Chen, and Said Musli. Funding for the work was provided by Iowa State University and the Department of Landscape Architecture. Typist Cheryl Sansgaard and students Steve Morgan, Nicole Horst, and Luke Slings helped the researchers digitize the field notes for these three counties.

These digital field notes are available in the form of MS Word document files and HTML Web pages through Iowa State University’s GLO GIS server.

14. What do the digital historic vegetation map files contain?

From 1992 to 1996, researchers in the ISU Department of Landscape Architecture digitized historic vegetation data from the township maps. Researchers annotated the maps by reading the field notes for each township. A total of 38 different vegetation types were digitized within the state. The vegetation types were not classified according to a predetermined classification. Rather, the names of the vegetation types were taken from the GLO surveyors’ descriptions, using their own words. Researchers followed the principle of keeping vegetation types separate and not aggregating them into fewer categories. In this way, others who use the data can aggregate according to their own needs.

ALE Swale
BAR Barrens
BAY Bayou
BRU Brush
CIT City
DRA Drain
FIE Field
GRO Grove
IFD Indian field
ISL Island
LAK Lake
MAR Marsh
MEA Meadow
OAK Oak barrens
OPE Openings
PPT Part prairie/part timber
PON Pond
POO Pool
PRA Prairie
RAV Ravine
RIV River (border)
ROU Rough
SAN Sandbar
SCA Scattering trees
SLU Slough
SPR Spring
SWA Swamp
SMR Swamp/marsh
THI Thicket
TIM Timber
TBR Timber/barrens
TSB Timber/scattering/barrens
TSO Timber/scattering/openings
VIL Village
WET Wetland
WIL Willows
WIN Windfall

15. What procedures were used to digitize the historic vegetation map data?

Township maps were digitized in sets by county in approximately the same order as the maps appear on the microfilm (from southeast to northwest): 14 counties in Phase 1 (1992-93), 25 in Phase 2 (1993-94), 31 in Phase 3 (1994-95), and 29 in Phase 4 (1995-96). Township maps were digitized using the following procedure:

  1. Print hard copy township maps from the microfilm
  2. Annotate maps with vegetation lines and labels by reading the surveyors’ field notes on microfilm
  3. Place each township map on 12"x12" digitizing tablet and rubbersheet to the township lines theme from Iowa DNR’s NRGIS server
  4. Digitize lines and label polygons using our custom AutoLISP commands in AutoCAD Rel. 12
  5. Verify digitized maps by visually comparing to source maps
  6. Import each file into ArcCAD to check for label errors, open polygons, and slivers
  7. Edit changes (if necessary) and verify digitized maps again
  8. Save files in PC Arc/Info format

For some counties, this procedure took as little as 4 hours (Grundy County). For larger, more complex counties, this procedure took up to 37 hours (Linn County). The average for all 99 counties was between 14 and 15 hours (Cerro Gordo, Crawford, Dallas, Delaware, Jasper, Monroe, Union, and Van Buren Counties). A major influence on the amount of time spent on each township map was the completeness and clarity of the surveyor’s lines representing vegetation.

Where the deputy surveyor's "rather crude sketches and plots" (topographies) were missing vegetation boundaries and labels, drafters at the Surveyor General's office in Dubuque may have filled in some of the missing information with help from field notes or recollections of deputy surveyors. In many cases, they must have mapped vegetation boundaries using data points (distances) along section lines then connected them with straight-line interpolations if no other information was available to guide them. In Iowa's Forest Area in 1832: A Reevaluation (1987, p. 120), George Thomson said, "Detailed reading of the survey notes casts considerable doubt upon both the definition of the forest then existing and the exact positioning of the forest boundary lines...there is reason to doubt that the forest boundaries drawn at the time of survey would satisfy today's ecologist, forester, farmer, tax assessor, or surveyor."

Where vegetation lines were missing from GLO township maps, we used the straight-line interpolation method described in the previous paragraph. On some occasions, other landform or water features shown on the maps guided us in drawing vegetation boundary lines. For example, in the absence of more definitive information from the field notes, a river or bluff line was used as a vegetation boundary. We made a concerted effort to read and reread field notes when the maps and notes were inconsistent or contained discrepancies. A common example of this was edge matching vegetation boundaries across township lines. It seems that this was seldom a concern of GLO surveyors; often, neighboring townships were surveyed by different deputy surveyors. They and the map drafters made little or no attempt to edge match adjacent townships. Our only recourse in edge-matching township maps was to connect open ends of vegetation boundaries with straight lines.

16. What do the digital field note files contain?

The digital files contain the text of the field notes. The text is arranged in the same double column format as the typescript. The left column lists distances (from the previous section corner) in chains and links. (The Gunter’s survey chain is 66 feet long and one link is 7.92 inches long. A chain is 100 links long. A mile is 80 chains long.) The right column lists the section corner, quarter corner, stream, valley edge, line tree, vegetation change ("leave prairie, enter timber"), or other feature at the distance specified in the left column.

The digital notes were prepared from the WPA typescript made in the late 1930s from the original manuscript. In Toward an Office-wide Policy: Citing Government Plats and Maps (manuscript on file in the Office of the State Archaeologist, Iowa City), Michael J. Perry (1993, p. 3) describes an additional set of microfilm available at the State Historical Society of Iowa: "The real WPA copies of the field notes and plats are on 16mm film at the SHSI. Apparently, these were copied from originals in the Secretary of State's collection. The field notes were typed, paginated, and assigned to volume numbers at the rate of about 4 townships per volume. Pagination is serial within volumes, and a total of 301 volumes were produced. Plat maps appear at the beginning of the notes for each township and are also paginated, but I've noticed that not all the township notes have accompanying maps, particularly in western Iowa. The reliability of the plats that are included appears to be better than the copies in the White Box Series. The WPA project was completed in 1938. The microfilms were produced as a preservation measure."

17. What procedure was used to digitize the field notes?

Field notes for the south half of Dallas County were scanned using a desktop scanner and converted to text using Optical Character Recognition (OCR) software (OmniPage ). Field notes for the north half of Dallas County were typed by a professional typist. After comparing the total amount of time required for each method, the notes for Polk County and Hamilton County were typed rather than scanned with OCR. This is because the typescript was difficult to scan, even after trying a variety of OCR software and scanning options. This time required for scanning and editing exceeded that required for typing. This may be due to the fact that we scanned the microfilm rather than the original typescript (which is in the state archives and not available for scanning).

18. What GIS research has been conducted with the digital data?

Two major lines of research are being conducted with the digital GLO data.

First, GIS descriptive models have been developed to explore definitions of historic vegetation and spatial relationships. In his 1995 MLA thesis, Mike Miller modeled ten GLO vegetation types in Fayette County. In his 1999 MLA thesis, Said Musli modeled GLO vegetation types in Hamilton County. In his 2000 MLA thesis, Patrick Brown modeled changes in habitat fragmentation in six counties in central Iowa. In his 2001 MLA thesis, Steve Morgan modeled changes in estimated surface runoff in the Little Beaver Creek watershed in Dallas and Polk Counties. Recent research by Paul Anderson modeled (1) areas in Iowa described as wetland types by GLO surveyors and (2) soil ratings (first rate, second rate, third rate) by GLO surveyors.

Second, Jane Chen, in her 1998 thesis developed a hypermedia database to digitally link the GLO township maps with the corresponding notes. This has led to more extensive research into digitizing field notes to create searchable text.

19. Are there opportunities for additional research?

Yes. As often happens in research projects, more questions are raised than answered. Here are ideas for some additional opportunities generated by previous research with GLO data:



  1. Digitize field notes for 96 other counties in Iowa
  2. Document the procedures used to create the typescript of GLO field notes in a WPA project of the 1930s
  3. Develop GIS descriptive models of all 38 vegetation types digitized from GLO township maps
  4. Explore the meanings of the vegetation terms used by the deputy surveyors in Iowa
  5. Document the cultural, educational, and work-related backgrounds of the 187 GLO deputy surveyors in Iowa
  6. Develop GIS descriptive models to compare GLO vegetation with historic vegetation from other data sources (such as soil maps and atlas maps)
  7. Digitize point and line features from GLO township maps (such as streams, trails, cabins, floodplains, mill sites, coal deposits, topographic features, and grave sites)

20. How can I get more information about the research?

See Paul Anderson's GLO Web page with a summary of his research work. The site include Adobe Acrobat files of his 1996 report to Iowa DNR.



Data limitations

21. How accurate were the GLO surveys?

Modern surveyors describe the GLO survey as one with low accuracy and lack of precision. When the survey began, the Federal government desperately needed money; one way that they could get it was from the sale of public lands. They needed a survey system that was efficient and could get the job done quickly. Euro-American settlers were beginning to populate unsettled areas at a rapid rate, even before these areas could be surveyed and opened for settlement. It became imperative that the Federal government survey those lands to maintain order. Probably the most important reason that the surveys were not as concerned with accuracy as surveys are today is because the price of land was low, often $1.25 per acre. Low land prices did not warrant any delay in the survey procedure. According to Hildegard Binder Johnson in Order Upon the Land (1976, p. 221), "Urgency of performance was the order of the day.  Surprisingly enough, a high percentage of accuracy was maintained ; in fact, in the upper Middle West, less than 5 percent of the surveys carried out before the contract system ended in 1910 were proved fraudulent, a remarkable achievement." 

According to J.S. Dodds in Original Instructions Governing Public Land Surveys of Iowa (1943), deputy surveyors were for the most part upstanding, conscientious employees. There were instances of fraud within the system, but for the most part, the surveyors were honest. In Public Land Surveys: History, Instructions, Methods, Lowell O. Stewart (1935, p. 49-50) said that the system of deputizing the surveyors required them to swear an oath to the correctness of their work. This and the threat of taking the required surety bonds were the only factors that helped assure the accuracy of these surveys.  "The real factor in determining accuracy of the surveys was the integrity of surveyors and their helpers.. In case of fraud, the government could...sue the deputy.  Moreover, conditions under which the deputies worked were so trying that they frequently pleaded extenuating circumstances.  In such a case, in response to a letter from the surveyor general in which certain errors were pointed out, one deputy reported how squatters obliterated or confused line markings on trees, set fire to the prairie and destroyed his camp.  Their purpose was to prevent the survey and subsequent opening of the land for sale."

Land surveying was done under a contract system. The deputy surveyor was contracted by the Surveyor General at $3.25 per mile for township lines and $2.75 per mile for section lines. They were required to pay for all of the expenses of the party until the contract was completed. The practice, however, began for the Surveyor General to finance deputies, thus taking on all responsibility and risk for their actions. Deputies were in charge of hiring members of their survey parties. The only requirement was that they also swear an oath. Instructions to the deputy surveyors said, "it is enjoined on you not to employ any person whose principles are known or supposed to be corrupt. . . nor is any one to be employed in the capacity above stated who is not a free white person, and who has not attained years of discretion sufficient to understand the nature and solemnity of an oath."

In Iowa's Forest Area in 1832: A Reevaluation (1987, p. 118), George Thomson described sources of error in the GLO surveys: "Field notes are often incomplete and flawed with errors that would either go undetected or would be ignored because the vastness of the surveying project and the low budget allocated to the contract surveyors prohibited correction."

In A History of the Rectangular Survey System (Washington, D.C.: Bureau of Land Management), C. Albert White (1983, p. 110) said that during the latter half of the 1840s, more and more examinations in the field were made by deputy surveyors under instructions from the Surveyor General.  Those examinations would prove to be largely fiction.  Just as a subdividing deputy seldom squealed on a fellow surveyor who did township lines, an examining deputy would seldom squeal on a subdividing deputy because that same person might be hired to examine his own work.

One of the early first GLO surveyors in Iowa was William Burt. In addition to being a deputy surveyor, he was also an assistant district judge, a Michigan Territory legislator, and a Justice of the Peace. In 1836, Burt also invented the solar compass, a replacement for the traditional magnetic compass that was often distracted by iron ore deposits. Burt was known for his reputation for honesty. When working as a survey examiner in Michigan, Burt found evidence of fraud within several surveys. As it turned out, these were surveys that he himself had subcontracted and signed for security. Nevertheless, he reported the fraud and resurveyed the areas at considerable personal time and expense.

In addition to problems with the magnetic compasses, there were problems with Gunter's Chain. It was not a good design for surveys through rugged territory. Much of the surveyor's time was spent cleaning the muck and the debris out of the chain. They did try to maintain the chain's measuring integrity by comparing the length to that of an unused chain. This checking procedure was supposed to take place at least every other day and any discrepancies were to be noted in the field books. According to the field notes (Volume 4, Book 21), the iron survey chain was 28 links per mile shorter in the winter than in the summer.

The Surveyor General had difficulty in finding qualified surveyors to hire as deputy surveyors. Deputy surveyors did not receive extensive training. Their outdoor skills were probably gained from experiences in farming or the military. Their observations and descriptions were influenced by their cultural and educational backgrounds. Also, many deputy surveyors who worked in Iowa had previously worked in GLO surveys. Some had surveyed in the Northwest Territories to the east. Others had surveyed in the Louisiana Purchase to the south. Their prior experiences undoubtedly influenced how the perceived and described the landscape as they surveyed Iowa.

22. How accurate are the digital GLO data?

Though GLO notes and maps constitute a useful data source, there are limitations in their use. When we use GLO data for purposes other than the intended use ("disposal" of land), we need to be aware of their limitations:



  1. Data collection over a more than 27-year period
  2. Transect survey (primarily along sections lines)
  3. Inconsistencies among 187 deputy surveyors (work experience, education, culture)
  4. Occasional changes in Surveyor General’s instructions to deputy surveyors
  5. Variability in weather conditions, equipment, and skills of survey party members
  6. Some areas were surveyed before counties were organized; other areas after
  7. Difficulties encountered with "preemptors" (squatters) and "hostiles" (Native Americans)
  8. Other data collection obstacles (wildlife, food and provisions, staffing survey parties)
  9. Difficulty in finding and using primary sources (field books) rather than secondary sources (copies)
  10. Differences between 19th century and current terms, language, and writing
  11. Potential errors in the typescript notes introduced by the WPA typists
  12. Potential errors introduced by the digitizing process (after data debugging and cleaning)

Last update:  1 April 2003