- Population: 7,348 (Change since 1990: -2.3%)
- Created: March 3, 1843
- County seat: Mound City
- Largest town: Mounds (Pop. 1,117)
- Name origin: Casimir Pulaski
- America (Unincorporated)
- Located between Mound City and Olmsted
- Latitude & Longitude: 37°08'18" N, 89°07'25" W
- Survey: T. 16 S., R. 1 E., Sec. 9
- Elevation: 355
- Precinct: America
- USGS Quad: Olmsted
- Karnak (Village)
- Population: 619 (Change since 1990: +6.5%)
- Located on IL 169 southwest of Belknap
- Latitude & Longitude: 37°17'37" N, 88°58'31" W
- Levings (Unincorporated)
- Located northeast of Olmsted
- Latitude & Longitude: 37°13'02" N, 89°03'42" W
- Survey: T. 15 S., R. 1 E., Sec. 12
- Elevation: 479
- Precinct: Olmsted
- USGS Quad: Olmsted
- Mound City (City)
- Population: 692 (Change since 1990: -9.5%)
- Located along IL 37 upstream from Cairo on the Ohio River
- Latitude & Longitude: 37°05'07" N, 89°09'45" W
- Name origin: Indian mounds
- Post office: May 31, 1856 - Now
- Mounds (City)
- Population: 1,117 (Change since 1990: -20.6%)
- Located northwest of Mound City along Old US 51
- Latitude & Longitude: 37°06'51" N, 89°11'52" W
- New Grand Chain (Village)
- Population: 233 (Change since 1990: -14.7%)
- Latitude & Longitude: 37°15'07" N, 89°01'16" W
- North Mounds (Unincorporated)
- Located just north of Mounds
- Latitude & Longitude: 37°07'23" N, 89°12'01" W
- Survey: T. 16 S., R. 1 W., Sec. 15
- Elevation: 335
- Precinct: Mounds
- USGS Quad: Cairo
- Olmsted (Village)
- Population: 299 (Change since 1990: -16.5%)
- Located northeast of Mound City
- Latitude & Longitude: 37°10'50" N, 89°05'20" W
- Founded: Sept. 9, 1872
- Perks (Unincorporated)
- Located between Wetaug and White Hill
- Latitude & Longitude: 37°18'35" N, 89°04'51" W
- Survey: T. 14 S., R. 1 E., Sec. 10
- Elevation: 346
- Precinct: Perks
- USGS Quad: Cypress
- Pryortown (Unincorporated)
- Located just east of I-57
- Latitude & Longitude: 37°11'25" N, 89°08'55" W
- Survey: T. 15 S., R. 1 E., Sec. 19
- Elevation: 410
- Precinct: Pulaski
- USGS Quad: Pulaski
- Pulaski (Village)
- Population: 274 (Change since 1990: -24.1%)
- Located on Old US 51 between Ullin and Villa Ridge
- Latitude & Longitude: 37°12'49" N, 89°12'21" W
- Founded: 1855
- Post office: Jan. 23, 1856 - Dec. 10, 1872 (Walbridge); Dec. 10, 1872 - Now (Pulaski)
- Spencer Heights (Unincorporated)
- Latitude & Longitude: 37°07'38" N, 89°11'41" W
- Survey: T. 16 S., R. 1 W., Sec. 14-15
- Elevation: 420
- Precinct: Mounds
- USGS Quad: Pulaski
- Ullin (Village)
- Population: 779 (Change since 1990: +93.8%)
- Located northeast of Tamms along Cache River
- Latitude & Longitude: 37°16'37" N, 89°10'60" W
- Villa Ridge (Unincorporated)
- Located between Pulaski and Mounds
- Latitude & Longitude: 37°09'31" N, 89°11'41" W
- Elevation: 398
- Precinct: Villa Ridge
- USGS Quad: Pulaski
- Post office: Aug. 12, 1853 - Jun. 26, 1861 (Valley Forge); Jun. 26, 1861 - Now (Villa Ridge)
- Map: 1876 atlas
- Wetaug (Unincorporated)
- Located south of Dongola
- Latitude & Longitude: 37°19'26" N, 89°09'60" W
- Survey: T. 14 S., R. 1 W.
- Elevation: 356
- Precinct: Wetaug
- USGS Quad: Dongola
Name origin
Named for Count Casimir Pulaski
| Year | Population | Percent change |
|---|
| 1850 | 2,265 | -- |
| 1860 | 3,934 | +73.7% |
| 1870 | 8,752 | +122.5% |
| 1880 | 9,507 | +8.6% |
| 1890 | 11,355 | +19.4% |
| 1900 | 14,554 | +28.2% |
| 1910 | 15,650 | +7.5% |
| 1920 | 14,629 | -6.5% |
| 1930 | 14,834 | +1.4% |
| 1940 | 15,875 | +7.0% |
| 1950 | 13,639 | -14.1% |
| 1960 | 10,490 | -23.1% |
| 1970 | 8,741 | -16.7% |
| 1980 | 8,840 | +1.1% |
| 1990 | 7,523 | -14.9% |
| 2000 | 7,348 | -2.3% |