County · Illinois

Williamson County, Illinois

Williamson County, Illinois. Williamson County had 67,225 residents in 2025 by the Census Bureau's estimate, up 0.1% since 2020, while Illinois shrank 0.8%. It holds 19 places (16 cities, villages and boroughs and 3 census-designated) and 18 census tracts. GEOID 17199.

Williamson County is the county of the Marion-Herrin, IL micropolitan statistical area (the Census Bureau's July 2023 delineation).

Residents, July 2025 estimate

67,225

Census Bureau estimate (no margin published)
2020 Census count: 67,153 · ACS 2020-2024: 66,876

Median household income

$65,604

±$3,466 (90% margin)
Illinois: $83,390

Median home value

$156,400

±$5,461 (90% margin)
Illinois: $263,300

Median gross rent

$930

±$37 (90% margin)
Illinois: $1,274

How many people live in Williamson County, and is it growing?

The 2020 Census counted 67,153 residents in Williamson County. The Census Bureau estimates 67,225 for July 1, 2025, up 0.1% since 2020, while Illinois shrank 0.8%. The 2020-2024 American Community Survey puts the population at 66,876 over 420 square miles of land.

July 2020→2021 −217 (66,910)
2021→2022 −366 (66,544)
2022→2023 +205 (66,749)
2023→2024 +325 (67,074)
2024→2025 +151 (67,225)

Williamson County in Illinois. Boundaries: Census Bureau 2024.

Counts, ACS 2020-2024 5-year estimates, with the change from 2015-2019
Measure	Williamson County	Illinois	Change since 2015-2019
Total population	66,876	12,694,798	−226
Households	28,983±394	5,036,449	+1,954
Average household size	2.23±0.03	2.46	−0.18
Housing units	32,084±58	5,457,452	+798

Williamson County's population since 2000

From 61,296 in 2000 to 67,225 in 2025: up 9.7%. The 2000, 2010 and 2020 figures are census counts. The 2005 figure is the Census Bureau's intercensal estimate, revised to fit the 2000 and 2010 counts and drawn on 2010 boundaries; 2015 and 2025 are July 1 estimates made from the census before them.

2000 Census 61,296
2005 (estimate) 63,875
2010 Census 66,357
2015 (estimate) 67,457
2020 Census 67,153
2025 (estimate) 67,225

Source: The 2000, 2010 and 2020 Census counts and the Census Bureau's population estimates (intercensal 2000-2010, Vintage 2020, Vintage 2025) · Census population estimates

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); PEP Vintage 2025 (CO-EST2025); 2020 Census · Check it at data.census.gov

What cities and towns are in Williamson County?

Williamson County holds 19 places: 16 cities, villages and boroughs (incorporated places) and 3 census-designated places. The largest is Marion with 17,148 residents (2025 estimate). Places that cross a county line are listed with the share of their 2020 residents who live in this county.

Places in Williamson County, ACS 2020-2024 5-year estimates. Ring: estimate with a coefficient of variation over 40%.

Marion	city	16,855	16,836±34	$56,912	$158,300	13.3%	100%
Herrin	city	12,352	12,226±71	$59,975	$113,300	14.5%	100%
Carterville	city	5,848	5,818±22	$62,337	$197,100	10.9%	100%
Johnston City	city	3,384	3,327±17	$42,465	$88,100	17.9%	100%
Cambria	village	1,505	1,300±247	$57,756	$143,800	18.5%	100%
Crainville	village	1,443	1,641±382	$65,461	$185,300	10.2%	100%
Energy	village	974	1,050±267	$65,357	$151,800	15.2%	100%
Hurst	city	764	700±191	$36,635	$68,600	31.4%	100%
Pittsburg	village	565	682±266	$53,203	$129,200	17.9%	100%
Creal Springs	city	505	324±102	$53,125	$55,800	21.3%	100%
Crab OrchardGEOID 1717094	CDP	356	394±186	$148,906	not published	5.6%	100%
WhiteashGEOID 1781165	CDP	279	301±235	$114,464	not published	0.0%	100%
BlairsvilleGEOID 1706444	CDP	243	231±120	$73,229	$181,500	5.2%	100%
BushGEOID 1710084	village	241	354±157	$55,357	$78,000	2.5%	100%
SpillertownGEOID 1771526	village	181	246±78	$81,250	$152,500	0.8%	100%
Colp	village	168	223±94	not published	$69,300	47.1%	100%
Freeman SpurGEOID 1727858	village	268	149±63	$35,000	$60,600	24.2%	53%
Stonefort	village	224	422±181	$56,477	$65,700	11.6%	53%
Carbondale	city	21,857	22,158±53	$32,128	$127,900	37.4%	0%

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 place-by-county parts · Check it at data.census.gov

Who lives in Williamson County?

The median resident of Williamson County is 41.6 years old; 21.3% are under 18 and 19.6% are 65 or older. The largest group is non-Hispanic white residents at 87.9%, then non-Hispanic Black residents at 4.3%. 2.0% of residents were born outside the United States.

Age, origin and education, ACS 2020-2024 5-year estimates. Race groups are non-Hispanic; Hispanic includes any race.
Measure	Williamson County	Illinois	Change since 2015-2019
Median age	41.6±0.3	39.0	no clear change
Under 18 years	21.3%±0.1 pts	21.8%	–
65 years and over	19.6%±0.2 pts	17.0%	–
Hispanic or Latino (any race)	2.9%	18.8%	+0.3 pts
White alone, not Hispanic	87.9%±0.3 pts	58.1%	−1.8 pts
Black or African American alone, not Hispanic	4.3%±0.4 pts	13.3%	no clear change
Asian alone, not Hispanic	1.4%±0.2 pts	5.9%	no clear change
American Indian and Alaska Native alone, not Hispanic	0.2%±0.1 pts	0.1%	–
Native Hawaiian and Other Pacific Islander alone, not Hispanic	0.0%±0.1 pts	0.0%	–
Two or more races, not Hispanic	3.2%±0.5 pts	3.4%	–
Some other race alone, not Hispanic	0.1%±0.2 pts	0.4%	–
Born outside the United States	2.0%±0.3 pts	14.7%	no clear change
Speak a language other than English at home (age 5+)	3.3%±0.5 pts	24.0%	–
Civilian veterans (age 18+)	8.7%±0.7 pts	4.8%	–
With a disability	19.1%±1.5 pts	12.1%	–
No health insurance coverage	4.6%±0.6 pts	6.9%	no clear change
High school graduate or higher (age 25+)	92.8%±0.8 pts	90.5%	–
Bachelor's degree or higher (age 25+)	26.2%±1.6 pts	37.8%	no clear change
Graduate or professional degree (age 25+)	10.6%±1.1 pts	15.3%	–
Moved from another state in the past year	2.0%±0.7 pts	1.6%	–

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov

What do households in Williamson County earn?

Half of Williamson County's 28,983 households earn less than $65,604 a year (±$3,466), against $83,390 in Illinois. In 2015-2019 it was $62,438 in 2024 dollars; the margins of error cannot tell the two periods apart. 13.8% of residents live below the poverty line.

Income and poverty in 2024 dollars, ACS 2020-2024 5-year estimates
Measure	Williamson County	Illinois	Change since 2015-2019
Median household income	$65,604±$3,466	$83,390	no clear change
Mean household income	$85,846±$3,467	$115,638	–
Per capita income	$37,284±$1,406	$46,406	+$2,363
People below the poverty line	13.8%±1.5 pts	11.8%	no clear change
Children under 18 below the poverty line	17.8%±4.1 pts	15.1%	no clear change
Households receiving SNAP	16.6%±1.7 pts	13.8%	–
Households with a broadband subscription	87.6%±1.4 pts	90.8%	–

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov

What does housing cost in Williamson County?

Owners occupy 70.7% of Williamson County's occupied homes and renters 29.3%. The median owner-occupied home is valued at $156,400 by its owner (±$5,461). The median renter pays $930 a month including utilities, and 35.2% of renters pay 35% or more of their income on rent.

Housing, ACS 2020-2024 5-year estimates
Measure	Williamson County	Illinois	Change since 2015-2019
Median home value (owner-occupied)	$156,400±$5,461	$263,300	+$14,993
Median gross rent	$930±$37	$1,274	no clear change
Renters paying 35% or more of income on rent	35.2%±4.6 pts	39.0%	no clear change
Median monthly owner costs, with a mortgage	$1,374±$57	$1,987	–
Owner-occupied homes	70.7%±1.9 pts	67.1%	no clear change
Housing units	32,084±58	5,457,452	+798
Homeowner vacancy rate	0.9%±0.5 pts	1.0%	–
Rental vacancy rate	5.2%±2.7 pts	5.0%	–
Single-family detached homes	74.9%±1.8 pts	58.2%	–
Mobile homes	6.8%±0.8 pts	2.3%	–
Built 2020 or later	1.3%±0.4 pts	0.7%	–
Built 1939 or earlier	14.7%±1.4 pts	20.2%	–

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov

How many new homes is Williamson County building?

Builders took permits for 141 new housing units across Williamson County in 2025 (68 single-family), 2.1 per 1,000 residents.

2019 178 units
2020 178 units
2021 93 units
2022 146 units
2023 129 units
2024 138 units
2025 141 units

Source: Building Permits Survey, annual county files 2019-2025, U.S. Census Bureau · Census Building Permits Survey

How do people in Williamson County get to work?

82.1% of Williamson County's workers drive alone and 8.8% work from home. The average trip to work takes 23.5 minutes. The unemployment rate in 2020-2024 averaged 5.0%.

Work and commuting, ACS 2020-2024 5-year estimates
Measure	Williamson County	Illinois	Change since 2015-2019
In the labor force (age 16+)	58.8%±1.3 pts	65.0%	–
Unemployment rate	5.0%±0.8 pts	5.8%	no clear change
Drove alone to work	82.1%±1.9 pts	65.9%	–
Carpooled	7.2%±1.4 pts	7.8%	–
Public transportation	0.3%±0.2 pts	5.8%	–
Walked	0.5%±0.2 pts	2.8%	–
Worked from home	8.8%±1.4 pts	15.9%	+5.1 pts
Mean travel time to work	23.5 min±1.2	27.8 min	no clear change

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov

What are Williamson County's census tracts?

Williamson County is divided into 18 census tracts. Among those with a reliable estimate, median household income runs from $41,825 (Tract 211) to $100,383 (Tract 213).

Census tracts of Williamson County, ACS 2020-2024 5-year estimates; sort by any column

Tract 20117199020100	Cambria (21%)	3,483	3,137±383	$52,773	$109,700	$647	20.9%
Tract 202.0117199020201	Carterville (54%)	5,552	5,883±511	$60,159	$175,500	$869	13.5%
Tract 202.0217199020202	Carterville (28%)	3,150	2,632±270	$97,833	$226,300	$1,153	11.4%
Tract 20317199020300	Herrin (28%)	5,067	5,379±549	$69,684	$174,800	$1,114	9.8%
Tract 20417199020400	Herrin	3,496	3,115±325	$43,800	$60,600	$881	16.5%
Tract 20517199020500	Herrin (93%)	3,400	3,365±465	$60,268	$118,100	$1,161	13.7%
Tract 20617199020600	Herrin (62%)	3,798	4,274±578	$71,734	$153,300	$986	15.3%
Tract 20717199020700	Johnston City (66%)	4,791	4,923±441	$46,362	$95,600	$956	17.2%
Tract 208.0117199020801	Pittsburg (22%)	2,806	2,489±392	$66,333	$216,800	$1,173	7.1%
Tract 208.0217199020802	Creal Springs (12%)	4,131	4,144±444	$83,846	$152,800	$825	11.2%
Tract 20917199020900	Marion (37%)	4,704	4,937±527	$80,125	$218,500	$976	8.3%
Tract 210.0117199021001	Marion	2,594	2,377±511	$49,250	$125,400	$764	16.2%
Tract 210.0217199021002	Marion (62%)	1,509	1,745±302	$65,733	$258,000	$1,029	18.0%
Tract 210.0317199021003	Marion (87%)	1,120	1,079±194	$43,942	$130,700	$882	25.4%
Tract 21117199021100	Marion (97%)	2,958	2,816±375	$41,825	$95,500	$1,020	18.3%
Tract 21217199021200	Marion (86%)	4,404	3,803±394	$62,159	$154,000	$884	11.7%
Tract 21317199021300	Marion (35%)	4,688	5,237±661	$100,383	$203,500	$771	9.5%
Tract 21417199021400	Carterville (1%)	5,502	5,541±436	$82,806	$242,400	$759	18.9%

Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Check it at data.census.gov

How does Williamson County compare with Illinois's other counties?

Williamson County's rank among Illinois's counties with a reliable estimate (1 = highest)
Measure	Rank
Population	22nd of 102
Growth 2020-2025	18th of 102
Residents per square mile	18th of 102
Median household income	61st of 102
Median home value	34th of 102
Median gross rent	22nd of 102
Poverty rate	38th of 102
Bachelor's degree or higher	26th of 102
Median age	61st of 102

Every county in Illinois

Source: PlainCities ranks from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed

How these figures are made: methodology and release checks · reading a margin of error · every state · corrections

Not on this page: crime, weather and schools for Williamson County are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.