The 1810 census of the Illinois Territory does not exist in its entirety, but what has survived is given here in full. It lists 1,310 heads of families, and, by age groups, the number of free white males and females in each household as well as the number of other free inhabitants and slaves owned. The total represented is over 7,000 persons.

The 1818 census, which is arranged by counties, makes up the bulk of this work. It lists over 4,000 heads of families and, for each household, shows the number of free white males over twenty-one, all other white inhabitants, free persons of color, and servants or slaves. This represents an estimated 20,000 persons. In addition, there are notations indicating which heads of households can be found in the federal and state censuses of Illinois for 1820.