Federal Township Plats of Illinois (18041891)


A grant from the Federal government through its Library Services and Technology Act (LSTA) has enabled the Illinois State Archives to digitize its 3,457 federal township plats of Illinois and present the images on this Web site. These hand drawn plats show Illinois’ landscape as it was before American settlement as well as legal surveying measurements. Occasionally the plats indicate man-made features, both Indian and European. The U.S. Surveyor General and his deputy surveyors drew these maps of “six miles square” townships or fractional townships in preparation for the Federal government’s sale of public lands. Today Illinois’ plats still have legal, historical, and scientific value. Now anyone having access to a computer can view the plats, previously available only at the Archives or at those few institutions having microfilm copies. In addition, the plats are available on a CD edition.

History of the U.S. Surveyor General

Land Ordinance of 1785
The Land Ordinance of 1785 created the rectangular survey system for mapping and sale of the western public lands of the United States. The federal statute established a coordinate system for locating townships based on the intersection of a north-south meridian and an east-west base line. It provided for the creation of townships of six miles square and, when necessary, fractional townships. Each township comprised 36 sections, each section having an area of one square mile (i.e., 640 acres). The law also required appointed surveyors to draw plats of the surveyed lands and empowered the Federal government to sell the surveyed lands to the public.

Office of U.S. Surveyor General
In 1796 Congress created the office of U.S. Surveyor General, giving it the responsibility of surveying public lands. The office operated independently until Congress placed it under the General Land Office (GLO) in 1836. In 1849 the newly established Department of Interior assumed responsibility for the GLO. The 1925 appropriations act for the Department of the Interior closed the office of Surveyor General. Surveying responsibilities remained with the GLO until its abolition in 1946. The Bureau of Land Management (BLM) assumed surveying duties on that date.

Surveying in Illinois
Early in the 19th century surveyors, operating under the authority of the U. S. Surveyor General, began surveying lands that would eventually comprise the state of Illinois. In 1803 the first survey of Illinois lands began with the boundaries of the Vincennes tract, its western region located in present-day Illinois. After completing surveys of the Vincennes tract, the Surveyor General’s deputy surveyors started in southern Illinois in 1806. In 1816 Congress established the office of Surveyor General for Illinois and Missouri, located in St. Louis, Missouri. The office’s deputy surveyors, moving northward, intersected Illinois’ northern boundary line in late 1831 and completed surveying the last townships in 1843. In 1855 the Federal government issued the last contract for the resurvey of an Illinois township. On October 31, 1863 the office of Surveyor General of Illinois and Missouri closed. In following years GLO surveyors conducted occasional surveys of unsurveyed areas such as islands and lakes (18681891).

Custody of Records
The 1796 legislation establishing the U.S. Surveyor General required the production of three copies of each plat. In 1869 the U.S. government transferred the Illinois records of the St. Louis office of the Surveyor General to the Governor of Illinois. In 1883 the Auditor of Public Accounts accepted custody of the records. Since 1957 the Illinois State Archives, operating under the Secretary of State, has maintained the Illinois records of the Surveyor General. The National Archives has custody of the copies of the plats originally sent to the Washington, DC headquarters and Illinois’ local land sales offices of the General Land Office.

About the Township Plats (1804-1891)

Description of Plats
The Archives’ record series, Federal Township Plats (RS 953.012), consists of 3,457 hand drawn maps of Illinois townships of six miles square and fractional townships showing natural and man-made features and vegetation. Plats indicate various types of natural features and vegetation including areas of prairie, barrens, timber, cliffs, mounds, ravines, bluffs, salt licks, salt springs, and mineral deposits as well as watercourses, swamps and bodies of water. For navigable watercourses, plats show surveys of bank meanders as well as islands, bars, rapids, cascades, and waterfalls. Plats provide previously established names of natural features such as rivers, prairies, and caves (e.g., “The Rock & Cave”). Man-made features are occasionally included such as wagon trails, roads, settlements, towns, fortifications, buildings, farm fields, and Indian traces and sites. Illinois’ plats are drawn to a scale of two inches to a mile.

A township plat, indicating the legal description of township, shows delineations of survey lines that deputy surveyors ran on the boundaries of each section (i.e., one square mile or 640 acres) or, when necessary, fractional section. The surveyor’s tool for the measurement of length was the chain, which measured 66 feet. A chain was composed of 100 links of 7.92 inches each. Surveying measurements and symbols include chains and links of interior and exterior section lines, especially when varying from standard eighty chains (i.e., one mile); chains and links of natural and man-made divisions of interior and exterior section lines; compass directions and chains and/or links of surveying offsets of interior and exterior section lines; directions of flow and chains and/or links of widths of watercourses at intersections of interior and exterior section lines; numbers of acres in township and in each section and, when necessary, half, quarter, quarter-quarter and fractional sections of township; and variations in degrees and minutes between true and magnetic meridians. For militia, improvement, and ancient claims of land, the plats note boundaries, survey and claim numbers, and numbers of acres as well as boundaries of Indian reservations. Plats generally include dated notes and certifications of the Surveyor General and/or deputy surveyors.

Drawing the Plats
The 18041825 plats originated from the hands of the deputy surveyors. During the course of surveying, deputy surveyors created certified and dated field notes consisting of survey measurements, notations of natural and man-made features and vegetation, and evaluations of the suitability of the soil for farming. Subsequently deputy surveyors drew certified and dated plats from the information provided by their field notes and crude plats. In reviewing the deputy surveyors’ plats, the Surveyor General frequently wrote dated correctional or conformable notes as well as his own dated certifications.

After 1825 the Surveyor General for Illinois and Missouri, located in St. Louis, Missouri, had sole responsibility for drawing certified plats. The Surveyor General created original plats by consulting the deputy surveyors’ field notes and “sketches” or rough plats. He also produced duplicate and, if necessary, correction plats by consulting the originals and field notes housed in his office. He infrequently prepared resurvey plats, using information from resurveys of townships. The St. Louis office drew its last plats in 1863. The Illinois State Archives maintains the field notes as record series, Federal Land Surveyors’ Field Notes (RS 953.005) and Field Notes of Private Surveys (RS 953.007). During 18681891 the Surveyor General produced the record series, Transcripts of Field Notes for Previously Unsurveyed Islands and Lakes (RS 953.008), and accompanying plats included with this record series.

Determining Original Survey Lines
A person may need to examine all the plats of a township to conduct surveying or scientific research. Joe D. Webber’s Early Public Land Surveys in the Northwest Territory and Procedures for the Retracement of Original Government Surveys in Illinois (Rochester, IL 1981) states that all plats of a township and the related field notes must be studied in determining original survey lines. For review of a township’s western and northern lines, he also recommends studying plats of adjacent townships. As evidence Webber cites omissions and errors found on some of the Surveyor General’s copies and revisions of deputy surveyors’ plats.  

Understanding the Rectangular Survey System

Illinois’ Meridians and Base Lines
We still locate and determine property boundaries of Illinois’ lands through the rectangular survey system.  The system divides Illinois into 36-square mile townships or fractional townships that are located in ranges west of the 2nd Principal Meridian or east or west of the 3rd or the 4th Principal Meridians. Townships are further located as north or south of base lines that serve as reference points for each meridian.

Determining Location of a Township
The legal description of a township determines its location on the Illinois Public Domain Land Tracts map. Refer to the legal description at the top of a plat to find the principal meridian for the township. Beginning at the intersection of the principal meridian and its base line, use the legal description’s township number to count north or south of the base line and range number to count east or west of the principal meridian. Through these steps you can locate your township. For example, if the legal description is Township 28N, Range 6E of the 3rd P.M., start at the intersection of the 3rd P.M. and the Centralia Base Line and count 28 townships north and 6 ranges east to find a township in the middle of Livingston County.

Divisions of a Township and a Section
The township is divided into 36 sections of 640 acres or one square mile. Each section can be further subdivided into quarter sections, half-quarter sections, or quarter-quarter sections. Occasionally geography limits surveys to fractional townships and sections. Examples of these subdivisions within a township are shown on the accompanying maps. Use the figures to determine location within a township and within a section.

The Surveyor General required a standard tool of measurement for conducting surveys. Surveyors used the chain of 100 links (66 feet). Each link measured 7.92 inches. One mile equaled 80 chains.

Surveying Problems and Solutions
The rectangular survey system had its limitations, some resulting from factors outside the surveyor’s control. Errors of surveying were inevitable considering the deficiencies of the available tools, the chain of 66 feet and the magnetic compass. Some of the early Surveyors General apparently did not fully understand the problem of the northward convergence of north-south meridians and failed to issue the necessary instructions. Other instances of error can be traced to carelessness or fraud. Some surveyors may have rounded their measures to the nearest five or ten links, a practice not helpful in efforts to connect to other survey points. Occasionally the Surveyor General required deputy surveyors to resurvey an area because of grossly inaccurate or fraudulent surveying.

Through the years, the Surveyor General revised his instructions to better deal with shortcomings of the system. Surveyors worked under seven revisions of surveying instructions during the period when Illinois was surveyed. In compliance with the Land Act of 1800, surveyors rectified a survey’s shortcomings by using a township’s northern row and western tier of sections for correction of overages and underages of distance and area. In 1818 the Surveyor General first provided instructions to rectify meridian convergence. For Illinois he established east-west “correction” lines at northward intervals of 24 to 60 miles, offsetting the new northern townships at the “correction” lines.

View the Plats

Before Viewing the Plats
For each geographical township the viewer generally will find two or more plats, each one having a different date of certification. The certification date indicates the date when the plat was drawn. The information on the plat reflects what the deputy surveyors saw and measured at the time of the survey. Surveyors began surveys of a township by running its exterior lines and, subsequently, interior lines, usually beginning at the southeast corner and working in progression from east to west and from south to north. As a result, the survey lines found on a plat may reflect information gathered at varying dates, occasionally a year or more apart. Deputy surveyors generally drew the 18041825 plats a few months after the completion of a township’s survey. After 1825 the Surveyor General drew all original and copies of plats, frequently long after the survey was conducted. He also created correction plats, which included revisions to original plats and, occasionally, resurvey plats. The dates of a township’s survey can be determined by consulting all of its plats and, if necessary, the surveyors’ field notes. The field notes are available at the Archives.

Find Your Plat
The images of a county’s geographical townships can be accessed from this county map. The county map indicates both geographical and civil township boundaries. The geographical townships of federal government plats do not necessarily coincide with the boundaries of a county’s civil townships. Federal government surveyors mapped the boundaries of geographical townships in accordance with coordinates established by the rectangular survey system. The citizens of a county established civil township boundaries as political entities. People unfamiliar with geographical townships should use the map’s boundaries of civil townships as a guide in locating the proper geographical township

By bringing the mouse pointer within the boundaries of a geographical township, a researcher can access a listing of the plat(s) of that township available for viewing. By further clicking on a plat number, the MrSID image of that plat will appear.

On georeferencing

The geographical term of georeference refers to the establishment of a relationship between points on a planar (i.e., sheet) map and known real world coordinates such as latitude and longitude. Fixing real world coordinates on a digital image of an Archives’ plat can be accomplished through geographic information systems (GIS) software. If a researcher is interested in obtaining uncompressed TIFF images of Illinois plats for georeferencing, please contact: Illinois State Archives, Norton Building, Springfield, Illinois 62706. E-mail: Illinois State Archives. Telephone: 217-782-3645.

On accessing the public domain database

One of the Archives’ Web databases, Illinois Public Domain Land Tract Sales, provides the researcher with an opportunity to determine the names of the first purchasers of the tracts of lands found on Illinois plats. By entering the legal description of a tract of land on this database, a researcher can obtain information regarding the purchaser’s name, purchase date, number of acres, price per acre, name of county in which the land is located, volume and page number of original entry in land sale registers, and variously, sale type, and purchaser’s sex and residence. The Web address for the database is http://www.cyberdriveillinois.com/departments/archives/databases/data_lan.html


Illinois State Archives

Dr. John Daly, Director
Dr. Wayne Temple, Deputy Director
Charles Cali, Concept Developer & Project Coordinator
Barbara Heflin, Illinois State Archives Webmaster
Robert Bailey, LSTA Grant Application Developer
Betty Strang, Plat Conservator
Elaine Evans, Indexes Developer
Karl Moore, Digital Image Quality Control

Department of Information Technology

Michael Standley, Secretary of State Webmaster
David Brodsky, Creative Director, Project Designer & Flash Developer
Sree Govindan, Programmer/Consultant
Emilee Mansholt, Graphic Designer
Gary Dameron, Jim Peters & Daniel Vilmure, System Support & Administration


Beth Sandore & Trevor Jones (University of Illinois)
Joe Dancel, Ted Slater, Katie Houghton, & Dave Steimling (Data Management Internationale)