Seneca, IL Demographics

A map of Seneca's Population by Race

Race	2024 Pop	2020 Pop	2024 %	2020 %
White	2,121	2,118	86.6%	90.0%
Hispanic	246	103	10.0%	4.4%
Multiracial	60	92	2.4%	3.9%
Black	22	17	0.9%	0.7%
Native American/Other	1	12	0.0%	0.5%
Asian	0	11	0.0%	0.5%

Seneca, Illinois has an estimated population of 2,450, an increase from the 2,353 recorded in the 2020 Census. The population is 86.6% White, 10.0% Hispanic, 2.4% Multiracial, 0.9% Black, 0.0% Asian, and 0.0% Native American/Other. This demographic dot map shows the population of Seneca, with one dot drawn for each person counted by the Census, color-coded by race.

Seneca has become considerably more 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 Seneca, that probability was 18.6% in 2020 and 24.0% in the most recent ACS estimates.

Seneca is ranked the 465th most populous place in Illinois, out of 1,461 places. This ranking is based on the Census definition of a place, which includes incorporated places like cities, towns, and villages, as well as unincorporated census-designated places (CDPs). Seneca was ranked the 472nd most populous place in the 2020 Census.

Seneca's White Population

2,121 residents of Seneca, or 86.6% of the population, identify as White. The share of White residents in Seneca is significantly higher than in Illinois overall, where 58.1% of the population is White. Seneca ranks 779th statewide in terms of White residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's White population has remained roughly the same. White residents' share of Seneca's population has decreased from 90.0% to 86.6%.

Seneca is more White than neighboring Marseilles (85.6% White), and Morris (82.9% White). Seneca is less White than neighboring Kinsman (91.7% White), Verona (88.2% White), and Ransom (94.7% White).

Seneca's Black Population

22 residents of Seneca, or 0.9% of the population, identify as Black. The share of Black residents in Seneca is considerably lower than in Illinois overall, where 13.3% of the population is Black. Seneca ranks 716th statewide in terms of Black residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's Black population has grown by an estimated 29.4%. Black residents' share of Seneca's population has remained roughly unchanged at 0.9%.

Seneca is more Black than neighboring Marseilles (0% Black), Kinsman (0% Black), Verona (0% Black), and Ransom (0% Black). Seneca is less Black than neighboring Morris (2.3% Black).

Seneca's Asian Population

0 residents of Seneca, or 0.0% of the population, identify as Asian. The share of Asian residents in Seneca is lower than in Illinois overall, where 5.9% of the population is Asian. Seneca ranks 663rd statewide in terms of Asian residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's Asian population has declined by an estimated 100.0%. Asian residents' share of Seneca's population has decreased from 0.5% to 0.0%.

Seneca is less Asian than neighboring Marseilles (3.9% Asian), Morris (0.6% Asian), and Ransom (0.4% Asian).

Seneca's Hispanic Population

246 residents of Seneca, or 10.0% of the population, identify as Hispanic. The share of Hispanic residents in Seneca is lower than in Illinois overall, where 18.8% of the population is Hispanic. Seneca ranks 568th statewide in terms of Hispanic residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's Hispanic population has grown by an estimated 138.8%. Hispanic residents' share of Seneca's population has increased from 4.4% to 10.0%.

Seneca is more Hispanic than neighboring Marseilles (5% Hispanic), Kinsman (8.3% Hispanic), Morris (9.7% Hispanic), and Ransom (2.4% Hispanic). Seneca is less Hispanic than neighboring Verona (11.4% Hispanic).

Seneca's Native American/Other Population

1 residents of Seneca, or 0.0% of the population, identify as American Indian/Alaska Native/Native Hawaiian/Pacific Islander/Other. The share of Native American/Other residents in Seneca is comparable to the share in Illinois overall, where 0.5% of the population is Native American/Other. Seneca ranks 512th statewide in terms of Native American/Other residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's Native American/Other population has declined by an estimated 91.7%. Native American/Other residents' share of Seneca's population has decreased from 0.5% to 0.0%.

Seneca is less Native American/Other than neighboring Marseilles (0.7% Native American/Other), and Morris (0.1% Native American/Other).

Seneca's Multiracial Population

60 residents of Seneca, or 2.4% of the population, identify as Multiracial. The share of Multiracial residents in Seneca is comparable to the share in Illinois overall, where 3.4% of the population is Multiracial. Seneca ranks 559th statewide in terms of Multiracial residents as a share of the population, out of 1,461 places.

Since the 2020 Census, Seneca's Multiracial population has declined by an estimated 34.8%. Multiracial residents' share of Seneca's population has decreased from 3.9% to 2.4%.

Seneca is more Multiracial than neighboring Kinsman (0% Multiracial), and Verona (0.4% Multiracial). Seneca is less Multiracial than neighboring Marseilles (4.8% Multiracial), and Morris (4.4% 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.