Monmouth, Illinois

Monmouth population, 2020 to 2024

Monmouth lost 277 residents from July 2020 to July 2024, a change of -3.1%. In the latest year it moved by +36. Among 330 Illinois places of 5,000 or more, that growth ranks 312th; the median place changed by -0.9%. The median place of 5,000+ in Illinois has 14,760 people, so Monmouth is 59% of it.

Monmouth covers 4.24 square miles of land and 0.02 of water, for 2,038 people per square mile of land. The median Illinois place of 5,000+ has 2,177, so Monmouth is close to the typical town.

What county Monmouth is in

All of Monmouth's residents live in Warren County, which had 16,217 residents in 2024. Monmouth holds 53.3% of the county's population. The shaded shape is on the map above; dots mark the eight nearest places.

ZIP codes in Monmouth

1 ZIP Code Tabulation Area (ZCTA) overlaps Monmouth by at least 10% of the ZCTA's or the city's land: 61462. ZCTAs are Census approximations of USPS ZIP code delivery areas. The list comes from the 2020 ZCTA to place relationship file, so a city that annexed land after 2020 may reach into ZIP codes not listed here.

Where Monmouth is

The Census internal point of Monmouth is at 40.914200, -90.643100. Springfield, the capital, is 94.2 miles SE in a straight line. The nearest larger place is Galesburg, IL (29,289 people), 14.1 miles away. The nearest city of 100,000 or more is Davenport, IA, 44.4 miles away.

Daylight in Monmouth

At 40.91° N, Monmouth gets about 15 h 07 min of daylight around the June solstice and 9 h 14 min around the December solstice, a swing of 5 h 53 min. Figures are sunrise to sunset from the SunCalc model for June 21 and December 21, 2026.

Places near Monmouth

The eight nearest incorporated places of 1,000+ in Illinois, measured between internal points. The closest is Galesburg, 14.1 miles away, with 29,289 people.