Alexander County, Illinois

Alexander County is a county in Illinois, United States, the state’s southernmost county, bounded by the Mississippi River on the west and the Ohio River on the south and east. It had a population of 5,240 at the 2020 census and covers 253 square miles (660 km2) centred near 37°11′N 89°20′W.

Cairo is the county seat, and its postal code is 62914. The county has one city, four villages, two census-designated places and thirteen unincorporated communities. Alexander County observes Central Time and carries FIPS code 17003.

Towns & Villages in Alexander County

Alexander County has twenty settled places on record. One, Cairo, is an incorporated city and the county seat; four are incorporated villages; two are census-designated places (CDPs) recognized by the Census Bureau but not separately incorporated; the rest are unincorporated communities with no municipal government of their own.

East Cape Girardeau sits directly across the Mississippi River from Cape Girardeau, Missouri, and shares its name with that larger city; the two are connected by the Emerson Memorial Bridge (US 60/62) but lie in different states. Cairo Junction is a rail crossing near Cairo, not a separate town in its own right, and is listed here only because it appears on older local maps.

ZIP Codes

• 62914 — Cairo
• 62957 — McClure
• 62962 — Miller City
• 62969 — Olive Branch
• 62988 — Tamms
• 62990 — Thebes
• 62993 — Unity (PO Box ZIP)

The county’s other listed places have no ZIP code of their own and are served by mail from the nearest post office town above.

Geography

Alexander County occupies the southern tip of Illinois, where the Mississippi and Ohio rivers converge just below Cairo. The terrain is low-lying river bottomland along both rivers, rising to gently rolling hills inland; the Cache River, a National Wetland Inventory priority wetland, crosses the county’s north side on its way to the Ohio. Of the county’s 253 square miles, 236 are land and 17 are water, a higher water share than almost any other Illinois county because of its position at the confluence.

Alexander County borders Union County to the north and Pulaski County to the east, both in Illinois. Across the Ohio River to the southeast lies Ballard County, Kentucky. Across the Mississippi River to the south and west lie Mississippi County, Scott County and Cape Girardeau County, all in Missouri.

Demographics

Alexander County had 5,240 residents at the 2020 census, down 36.4 percent from 2010 — the steepest ten-year population decline of any county in the United States over that period, driven largely by the 2013 closure of Tamms Correctional Center. Cairo, the seat, is the largest place with 1,733 residents; Olive Branch is the second largest at 650. The county’s median household income runs well below the Illinois median of $80,306, reflecting the loss of the prison payroll and decades of population decline along the river towns. Population density stands at roughly 22 people per square mile, among the lowest in southern Illinois.

Economy & Local Life

Agriculture, primarily corn, soybeans and some fruit orchards on the higher ground, and river-related transportation and logistics along the Mississippi and Ohio are the county’s main economic activity. Cairo’s port and rail connections once made it a major 19th-century shipping hub; today the local economy is smaller, anchored by county government, a handful of small manufacturers, and services in Cairo and Tamms. The Shawnee National Forest reaches into the county’s northeastern corner, drawing some hunting and outdoor recreation traffic.

History

Alexander County was organized in 1819, carved out of Union County, and named for William M. Alexander, a physician who later served as speaker of the Illinois House of Representatives. The county seat moved several times in its early decades — from America in 1819 to Unity in 1833, then Thebes in 1843, before settling permanently at Cairo in 1860. Cairo’s position at the confluence of the Mississippi and Ohio rivers made it a strategically important Union supply base and training ground during the Civil War, and the town grew into a significant river port through the late 1800s and early 1900s before a long economic decline set in over the 20th century.

Getting There

Interstate 57 crosses the county’s northern end, and U.S. Routes 51 and 62 run through Cairo, connecting the county to Missouri and Kentucky over Mississippi and Ohio River bridges.

• Cape Girardeau, Missouri — 10 miles west of Cairo
• Paducah, Kentucky — 40 miles east
• Carbondale, Illinois — 45 miles north
• Memphis, Tennessee — 150 miles south

The nearest commercial airport is Cape Girardeau Regional Airport in Missouri.

Frequently Asked Questions

Where is Alexander County?
It is in the southernmost tip of Illinois, United States, at the confluence of the Mississippi and Ohio rivers.

What is the population of Alexander County?
It had a population of 5,240 at the 2020 census.

How big is Alexander County?
It covers 253 square miles (660 km2), of which 236 square miles is land and 17 square miles is water.

What is the county seat of Alexander County?
Cairo is the county seat.

How many towns are in Alexander County?
The county has one city, four villages, two census-designated places and thirteen unincorporated communities on record.

What ZIP codes are in Alexander County?
62914 (Cairo), 62957 (McClure), 62962 (Miller City), 62969 (Olive Branch), 62988 (Tamms), 62990 (Thebes) and 62993 (Unity, a PO Box ZIP).

Why did Alexander County’s population drop so sharply?
The closure of Tamms Correctional Center in 2013, combined with decades of decline in river-based industry around Cairo, drove the steepest ten-year population loss of any U.S. county between 2010 and 2020.

More counties in this state: Towns and villages in Illinois.