This collection contains a portion of the census of Illinois Territory in 1810. In particular, it contains a 26-page photostat and a 101-page transcript of this portion which lists "Persons within the division allotted to Thomas C. Patterson, November 24, 1810." There are categories for "Free White Males," "Free White Females," and "All other Free Persons, Except Indians, Not Taxed." The areas mentioned are Kaskaskia, Springfield Township, Big Bay, and Clear Creek. There is a summary at the end showing a total population of 7,275.
The collection also includes a five-page typed tabulation of a portion of the 1818 census.
These materials were found in 1959 among the personal papers of Clarence W. Alvord in a vault in Lincoln Hall, University of Illinois. A year later, the original was photostated and deposited in the Illinois State Archives. By that point, Margaret Cross Norton had edited Illinois Census Returns, 1810, 1818, Vol. 24 of the Collections of the Illinois State Historical Library (Springfield, 1935).