Alexander County, Illinois
County seat: Cairo · Population 4,570 (2025) · 235 sq mi
Alexander County is the 99th most populous of Illinois's 102 counties, with 4,570 people (2025 estimate). Its county seat is Cairo. It is part of the Southern region, one of the 10 Illinois economic development regions (DCEO). The map shows its 5 cities and towns and the 6 neighboring counties.
Alexander County facts
- County seat
- Cairo
- Population (2025 estimate)
- 4,570 −12.8% since 2020
- Land area
- 235 sq mi 97th largest of 102
- Water area
- 17 sq mi
- Population density
- 19 per sq mi
- Established
- 1819
- Named after
- William M. Alexander American physician and politician
- Largest city
- Cairo 1,515
- Median household income
- $47,043
- Cities and towns
- 5 plus 2 CDPs
- ZIP codes
- 8
- Time zone
- Central
- FIPS code
- 17003
Cities and towns in Alexander County
Alexander County has 5 incorporated cities, towns and villages. Populations count the people living inside Alexander County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Cairo (county seat) | City | 1,515 | |
| Tamms | Village | 373 | |
| East Cape Girardeau | Village | 251 | |
| McClure | Village | 223 | |
| Thebes | Village | 181 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Olive Branch | 499 | |
| Unity | 77 |
ZIP codes in Alexander County
8 ZIP codes reach into Alexander County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 62914
- 62952 also Union County
- 62957 also Union County
- 62962
- 62969
- 62988
- 62990
- 62992 also Pulaski County
Population of Alexander County, 2020–2025
Alexander County shrank by 669 people (−12.8%) between April 2020 and July 2025: 265 more deaths than births and a net loss of 401 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 5,172 |
| 2021 | 5,026 |
| 2022 | 4,857 |
| 2023 | 4,727 |
| 2024 | 4,611 |
| 2025 | 4,570 |
Neighboring counties
- Pulaski County east · 4,820 people
- Mississippi County, Missouri south · 12,003 people
- Scott County, Missouri southwest · 37,975 people
- Union County north · 16,656 people
- Ballard County, Kentucky southeast · 7,594 people
- Cape Girardeau County, Missouri northwest · 83,999 people
Printable Alexander County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (95 KB)
- PNG (2400 px) (99 KB)
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Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
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