| County | Average Income |
| DuPage |  $38,398 |
| Lake | $38,248 |
| McHenry | $32,408 |
| Monroe | $32,334 |
| Kendall | $31,856 |
| Will | $30,407 |
| Woodford | $30,401 |
| Cook | $30,048 |
| McLean | $29,960 |
| Kane | $29,730 |
| Sangamon | $29,686 |
| Peoria | $28,979 |
| Piatt | $28,930 |
| Jo Daviess | $28,529 |
| Grundy | $28,075 |
| Tazewell | $27,838 |
| Menard | $27,577 |
| Clinton | $27,527 |
| De Witt | $27,222 |
| Carroll | $27,103 |
| Madison | $26,797 |
| Henry | $26,644 |
| Boone | $26,559 |
| Putnam | $26,493 |
| Mercer | $26,468 |
| Scott | $26,347 |
| Ogle | $26,331 |
| Rock Island | $26,284 |
| Bureau | $26,259 |
| Washington | $26,247 |
| Stark | $26,157 |
| Ford | $26,042 |
| Effingham | $26,029 |
| Marshall | $25,985 |
| Macon | $25,948 |
| Calhoun | $25,822 |
| Jersey | $25,682 |
| La Salle | $25,641 |
| St. Clair | $25,504 |
| Lee | $25,484 |
| Champaign | $25,455 |
| Iroquois | $24,884 |
| Henderson | $24,684 |
| Clark | $24,652 |
| Adams | $24,631 |
| Crawford | $24,535 |
| Winnebago | $24,404 |
| Macoupin | $24,267 |
| White | $24,150 |
| Morgan | $24,082 |
| DeKalb | $24,063 |
| Whiteside | $24,062 |
| Gallatin | $24,055 |
| Moultrie | $23,985 |
| Mason | $23,967 |
| Douglas | $23,870 |
| Jasper | $23,859 |
| Edgar | $23,724 |
| Stephenson | $23,695 |
| Kankakee | $23,535 |
| Livingston | $23,512 |
| Christian | $23,340 |
| Wayne | $23,242 |
| Richland | $23,236 |
| Shelby | $23,233 |
| Wabash | $23,123 |
| Hancock | $23,088 |
| Bond | $23,081 |
| Schuyler | $23,075 |
| Williamson | $22,840 |
| Greene | $22,466 |
| Hardin | $22,457 |
| Cumberland | $22,292 |
| Coles | $22,263 |
| Jefferson | $22,201 |
| Fayette | $22,194 |
| Marion | $21,696 |
| Knox | $21,653 |
| Randolph | $21,600 |
| Montgomery | $21,550 |
| Hamilton | $21,510 |
| Massac | $21,466 |
| Fulton | $21,396 |
| Saline | $21,341 |
| Logan | $21,255 |
| Vermilion | $21,169 |
| Clay | $21,111 |
| Cass | $20,894 |
| Pope | $20,885 |
| Edwards | $20,758 |
| Warren | $20,744 |
| Pike | $20,637 |
| Union | $20,497 |
| Franklin | $20,233 |
| Jackson | $19,943 |
| McDonough | $19,897 |
| Brown | $19,180 |
| Perry | $19,151 |
| Lawrence | $18,576 |
| Johnson | $18,560 |
| Pulaski | $18,553 |
| Alexander | $14,222 |
US-Places.com
Illinois Income by County -
Average income
The graph below ranks each Illinois County by Average income according to the 2012 census estimates.