Seneca, Illinois

Seneca population, 2020 to 2024

Seneca lost 35 residents from July 2020 to July 2024, a change of -1.5%. In the latest year it moved by -3.

Seneca covers 6.21 square miles of land and 0.37 of water, for 372 people per square mile of land. The median Illinois place of 5,000+ has 2,177, so Seneca is less dense than the typical town.

The 2 counties Seneca spans

Seneca crosses county lines. The Census county-part estimates split its 2,310 residents as follows; LaSalle County holds 99.6% of them. The shaded shapes are on the map above; dots mark the eight nearest places.

ZIP codes in Seneca

2 ZIP Code Tabulation Areas (ZCTAs) overlap Seneca by at least 10% of the ZCTA's or the village's land: 60450, 61360. ZCTAs are Census approximations of USPS ZIP code delivery areas. The list comes from the 2020 ZCTA to place relationship file, so a village that annexed land after 2020 may reach into ZIP codes not listed here.

Where Seneca is

The Census internal point of Seneca is at 41.302600, -88.614700. Springfield, the capital, is 118.4 miles SSW in a straight line. The nearest larger place is Marseilles, IL (4,779 people), 3.7 miles away. The nearest city of 100,000 or more is Joliet, IL, 28.3 miles away.

Daylight in Seneca

At 41.30° N, Seneca gets about 15 h 10 min of daylight around the June solstice and 9 h 11 min around the December solstice, a swing of 5 h 58 min. Figures are sunrise to sunset from the SunCalc model for June 21 and December 21, 2026.

Places near Seneca

The eight nearest incorporated places of 1,000+ in Illinois, measured between internal points. The closest is Marseilles, 3.7 miles away, with 4,779 people.