Williamson County Demographics

A map of Williamson County's Population by Race

Race	2024 Pop	2020 Pop	2024 %	2020 %
White	58,776	58,193	87.9%	86.7%
Black	2,864	2,809	4.3%	4.2%
Multiracial	2,158	3,155	3.2%	4.7%
Hispanic	1,947	1,779	2.9%	2.6%
Asian	935	771	1.4%	1.1%
Native American/Other	196	446	0.3%	0.7%

Williamson County, Illinois has an estimated population of 66,876, a less than 1% change from the 67,153 recorded in the 2020 Census. The population is 87.9% White, 4.3% Black, 3.2% Multiracial, 2.9% Hispanic, 1.4% Asian, and 0.3% Native American/Other. This demographic dot map shows the population of Williamson County, with one dot drawn for each person counted by the Census, color-coded by race.

Williamson has become less racially diverse since the 2020 Census. It is considerably less diverse than Illinois overall. Demographers use a diversity index to measure the probability that two randomly selected individuals belong to different racial or ethnic groups. In Williamson County, that probability was 24.4% in 2020 and 22.4% in the most recent ACS estimates.

Williamson County is ranked the 22nd most populous county in Illinois, out of 102 counties. Williamson County was ranked the 22nd most populous county in the 2020 Census.

Williamson County's White Population

58,776 residents of Williamson County, or 87.9% of the population, identify as White. The share of White residents in Williamson County is significantly higher than in Illinois overall, where 58.1% of the population is White. Williamson County ranks 58th statewide in terms of White residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's White population has grown by an estimated 1.0%. White residents' share of Williamson County's population has increased from 86.7% to 87.9%.

Williamson County is more White than neighboring Johnson County (80.1% White), and Jackson County (71.3% White). Williamson County is less White than neighboring Franklin County (94.1% White), Saline County (91.3% White), and Union County (89.5% White).

Williamson County's Black Population

2,864 residents of Williamson County, or 4.3% of the population, identify as Black. The share of Black residents in Williamson County is lower than in Illinois overall, where 13.3% of the population is Black. Williamson County ranks 39th statewide in terms of Black residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's Black population has grown by an estimated 2.0%. Black residents' share of Williamson County's population has remained roughly unchanged at 4.3%.

Williamson County is more Black than neighboring Franklin County (0.4% Black), Saline County (3.1% Black), and Union County (0.9% Black). Williamson County is less Black than neighboring Johnson County (7.8% Black), and Jackson County (13.9% Black).

Williamson County's Asian Population

935 residents of Williamson County, or 1.4% of the population, identify as Asian. The share of Asian residents in Williamson County is slightly lower than in Illinois overall, where 5.9% of the population is Asian. Williamson County ranks 23rd statewide in terms of Asian residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's Asian population has grown by an estimated 21.3%. Asian residents' share of Williamson County's population has remained roughly unchanged at 1.4%.

Williamson County is more Asian than neighboring Franklin County (0.4% Asian), Johnson County (0.2% Asian), Saline County (0.5% Asian), and Union County (0.6% Asian). Williamson County is less Asian than neighboring Jackson County (3.7% Asian).

Williamson County's Hispanic Population

1,947 residents of Williamson County, or 2.9% of the population, identify as Hispanic. The share of Hispanic residents in Williamson County is significantly lower than in Illinois overall, where 18.8% of the population is Hispanic. Williamson County ranks 56th statewide in terms of Hispanic residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's Hispanic population has grown by an estimated 9.4%. Hispanic residents' share of Williamson County's population has remained roughly unchanged at 2.9%.

Williamson County is more Hispanic than neighboring Franklin County (2% Hispanic), and Saline County (2.2% Hispanic). Williamson County is less Hispanic than neighboring Johnson County (4.5% Hispanic), Union County (5.5% Hispanic), and Jackson County (5.3% Hispanic).

Williamson County's Native American/Other Population

196 residents of Williamson County, or 0.3% of the population, identify as American Indian/Alaska Native/Native Hawaiian/Pacific Islander/Other. The share of Native American/Other residents in Williamson County is comparable to the share in Illinois overall, where 0.5% of the population is Native American/Other. Williamson County ranks 9th statewide in terms of Native American/Other residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's Native American/Other population has declined by an estimated 56.1%. Native American/Other residents' share of Williamson County's population has remained roughly unchanged at 0.3%.

Williamson County is more Native American/Other than neighboring Johnson County (0.2% Native American/Other), Saline County (0.2% Native American/Other), and Union County (0.1% Native American/Other). Williamson County is less Native American/Other than neighboring Jackson County (1.1% Native American/Other).

Williamson County's Multiracial Population

2,158 residents of Williamson County, or 3.2% of the population, identify as Multiracial. The share of Multiracial residents in Williamson County is comparable to the share in Illinois overall, where 3.4% of the population is Multiracial. Williamson County ranks 11th statewide in terms of Multiracial residents as a share of the population, out of 102 counties.

Since the 2020 Census, Williamson County's Multiracial population has declined by an estimated 31.6%. Multiracial residents' share of Williamson County's population has decreased from 4.7% to 3.2%.

Williamson County is more Multiracial than neighboring Franklin County (2.8% Multiracial), and Saline County (2.6% Multiracial). Williamson County is less Multiracial than neighboring Johnson County (7.2% Multiracial), Union County (3.4% Multiracial), and Jackson County (4.7% Multiracial).

Sources: Most recent population estimates are from the 2020-2024 American Community Survey 5-Year Estimates. 2020 population counts and map data are from 2020 Census State Redistricting Data. Geographic data are from Census TIGER/Line Shapefiles.