City in Warren County, Illinois · 4.2 sq mi · 2,004 people per sq mi
About 8,500 people live in Monmouth. The typical household earns $61,138, and the median resident is 34.1 years old.
2026 projection
From 8,923 in 2020
Poverty rate 17.71%
Men 33.2 · Women 36.2
1850–2026
8,502
2026 projection
4.7% since 2020 (decrease)
Source: U.S. Census Bureau decennial counts and annual estimates. 2026 is a projection. Values between recorded years are interpolated.
Use the left and right arrow keys to inspect population observations.
1850–2026
8,502
2026 projection
4.7% since 2020 (decrease)
Source: U.S. Census Bureau decennial counts and annual estimates. 2026 is a projection. Values between recorded years are interpolated.
Use the left and right arrow keys to inspect population observations.
| 2026 | 8,502 | -97 | 1.13% |
|---|---|---|---|
| 2025 | 8,599 | +64 | 0.75% |
| 2024 | 8,535 | +5 | 0.06% |
| 2023 | 8,530 | -58 | 0.68% |
| 2022 | 8,588 | -227 | 2.58% |
| 2021 | 8,815 | -108 | 1.21% |
| 2020 | 8,923 | +53 | 0.60% |
| 2019 | 8,870 | -84 | 0.94% |
| 2018 | 8,954 | -84 | 0.93% |
| 2017 | 9,038 | -83 | 0.91% |
Showing 10 of 33 years.
U.S. Census Bureau, 2024 ACS 5-year estimates · Table S0101
Each square is about 1% of residents (roughly 86 people).
Hispanic or Latino residents can be of any race. All other groups exclude Hispanic residents.
U.S. Census Bureau, 2024 ACS 5-year estimates · Table B03002
Half of households earn more, half earn less
Typical yearly pay for a worker 25 or older.
About 1 in 6 residents
36% of residents age 15 and older are married.
| Status | Overall | Male | Female |
|---|---|---|---|
| Married | 36% | 40% | 31% |
| Never married | 46% | 48% | 44% |
| Divorced | 10% | 10% | 11% |
| Widowed | 7% | 2% | 10% |
| Separated | 2% | <1% | 4% |
U.S. Census Bureau, 2024 ACS 5-year estimates · Table S1201
10 sources, all from the U.S. Census Bureau