ZIP Codes of Williamson County, IL

Population & People
Population & People
Total Population
63,233
Household Income
Household Income
Median Income
$56,069
Housing
Housing
Total Housing Units
30,526
Business & Economy
Business & Economy
Total Businesses
1,553
Employment
Employment
Employment Rate
55.61%
Education
Education
Bachelor's Degree+
26.20%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 11 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:11 ZIP Codes (7 Standard, 4 PO Box, 0 Unique) [See All]
Area Codes:618 / 730
Timezone:Central (GMT -06:00)
Local Time:2:12:04 PM
Population:63,233 [See All]
FIPS:17199
CBSA:Marion-Herrin, IL
Land Area:333 sq mi
Water Area:13 sq mi
Coordinates:37.7800, -88.9940
Quick Link:
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Wide geographic spread
ZIPs range from 149.1 sq mi down to 2.09 — a 71× sprawl ratio.

Standout ZIPs in this County


Most Populous
Marion · 27,793 people
44.0% of county total
Highest Income
Creal Springs · $74,245 median
1.3× county average
Largest Land Area
Marion · 149.1 sq mi
Spans the most ground
Fastest Growth
Carterville · 8.9% (10-yr)
9,787 → 10,658 residents
Most Educated
Carterville · 40.2% bachelor's+
2,926 of 7,280 adults 25+

Things worth knowing about Williamson County


63,233 residents live across 11 ZIPs covering 333 sq mi, served by 11 distinct USPS-recognized cities.

Population moved from 63,443 to 63,233 from 2014 to 2024 — a -0.3% change. 3 ZIPs gained residents, 8 lost.

The county's wealthiest ZIP 62922 (Creal Springs, $74,245 median) and poorest ZIP 62915 (Cambria, $31,875) are 20.7 miles apart — a 2.3× income gap across local geography.

Median home values vary 2.7× across this county — from $74,500 in 62949 (Hurst) to $200,200 in 62918 (Carterville).

Density varies 43× across the county — from 41 people/sq mi in 62922 (Creal Springs) to 1,742 in 62915 (Cambria).

Educational attainment ranges from 15.8% bachelor's+ in 62951 (Johnston City) to 40.2% in 62918 (Carterville) — the breadth of educational profiles across the area.

Within Illinois, this is the #23 most populous of 102 counties and ranks #95 for median household income .

Weighted by population, the typical household earns about $66,482 across the county — reflecting what a typical resident sees, not a simple ZIP average.

26.2% of adults age 25+ hold a bachelor's degree or higher (11,924 of 45,509 reporting).

7 Standard delivery, 4 PO Box only, 0 single-entity Unique ZIPs serve this county.

All ZIP Codes in Williamson County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
62959MarionStandard27,793$71,063149.11.4%
62948HerrinStandard12,758$60,97518.2-1.7%
62918CartervilleStandard10,658$70,92041.88.9%
62951Johnston CityStandard5,342$50,65729.3-3.3%
62922Creal SpringsStandard2,608$74,24564.0-19.5%
62974PittsburgStandard1,536$64,10726.0-0.6%
62933EnergyStandard1,101$67,7942.1-1.0%
62949HurstPO Box702$37,3081.6-12.5%
62915CambriaPO Box384$31,8750.26.1%
62921ColpPO Box2330.0-57.6%
62841Freeman SpurPO Box118$31,7501.0-15.7%

Adjacent & Nearby Counties