Possible Brick Walls of Jefferson Co, IL.

1790 both Knox Co or St. Clair Co,  <The United States>
North West Territory   <of the Ohio River>
1795 Choice of three; Knox, St.Clair, or Randolph
Co,<The United States> North West Territory <of the
Ohio River>. 
1801 St.Clair or Randolph Co, Indiana Territory
<There is a tax list in a book for Indiana Territory>
1803 Randolph Co, Indiana Territory
1809 Randolph Co, Illinois Territory
1812 Randolph Co or Gallatin, Illinois Territory
1813 Gallatin Co, Illinois Territory
1815 Edward Co or White Co, Illinois Territory
1816 Edward Co or White Co, Illinois Territory
1817 Edward Co or White Co, Illinois Territory
1818 Edward Co or White Co, Illinois Territory
1819 Jefferson Co, IL included 3/4 of present, Marion
Co, IL
1821 Jefferson Co, IL included 1/2 of present,Marion
Co, IL
1823 present Jefferson Co, IL and Marion Co, IL

When researching a county, it is advisable to check
all the surrounding counties. Also, to check varies
maps including government, railroad surveys, platt
maps, school districts, military (federal, state, &
county),etc. 

Remember, when a river freezes, it may be in county of
lest resistance for recording record. 

Remember the old joke: If the bedroom was in one
county- all births would be found there and if the 
parlor was in another county- all marriages would be
there.