Illinois State Library

General Land Office Plats

The Original Government Surveys Of Illinois and the Field Notes.

The Illinois State Archives holds the originals of both titles above. However, the Archives filmed them many years ago and film copies were scattered in various non-library sites around the state. The Illinois State Library now owns microfilm copy of both sets.

The government surveyors in the early 19th century took notes in the field as they surveyed and left monuments of the public land survey system (the township and range system) on the ground. When the fieldwork was completed, they drew maps from their notes. The maps, township by township, became what are labeled Illinois Township Plats (I333.08 ILLI in the Map Reading Room). The field notes are labeled Illinois Survey Field Notes (I333.08 ILLI2 in the Map Reading Room).

No personal names appear on these two types of records, but they do note land features, such as timber, prairie, lakes, marshes, etc. (One of the research uses for the surveys nationally is pre-settlement vegetation). These surveys are the earliest detailed maps and predate our county land ownership maps and atlases. The dates vary widely. The surveyors began in southern Illinois and worked their way north (see Illinois Libraries, January 1971, p. 34 for dates when various parts of Illinois were surveyed).

The index to the plats and the field notes is a homemade index map done by the Illinois State Archives staff on an Illinois Department of Transportation outline map of the state. Township and range system must be identified to use the index map. A more legible field note index was drawn in four sheets by A. Wolfinbarger. Copies are available in the Map Reading Room. The numbers on the index maps refer to volumes and pages of the hard copy, not reel numbers, but the hard copy volume and page numbers are on the reel labels. Most of the state has two plats: bottom number for the earlier set and the top number for the second set drawn later. The State Archives has since received funding to put the plats on the Web in original color at http://landplats.ilsos.net/ and on county CD-ROMs. The non-circulating CD-ROMs (SOFTWARE I333.08 ILLI) are in the Map Reading Room. The Illinois Natural History Survey published a CD-ROM set of the plats geo-rectified from the microfilm (SOFTWARE I333.08 ILLI2).

These microfilms do circulate. There is only one copy at the State Library of the field notes and tract books, but it is marked c.2, and cataloged as an Illinois document. There are two copies of the seven reels of plat microfilm.