Population in Alton, IL
Population in Alton, IL was 25,013 in 2025, according to the U.S. Census Bureau. That is down 0.1% from 2024. That is the 90th highest of 225 cities in 2025.
Population in Alton, IL, 2020 to 2025
All 6 values
| Period | persons |
|---|---|
| 2025 | 25,013 |
| 2024 | 25,049 |
| 2023 | 25,133 |
| 2022 | 25,269 |
| 2021 | 25,468 |
| 2020 | 25,640 |
Compared with Illinois and United States
| Place | 2025 |
|---|---|
| Alton, IL | 25,013 |
| Illinois | 12,719,141 |
| United States | 341,784,857 |
Rankings
Definition
Resident population. Spain and the EU: 1 January, with Spanish figures from the official municipal register (Padrón). Norway: Statistics Norway, 1 January. United States: Census Bureau population estimates for 1 July. United Kingdom regions and local authorities: Office for National Statistics estimates for 30 June. Other countries and the World: World Bank mid-year estimates, which count all residents regardless of legal status or citizenship.
The World Bank series exists for every country, so use it (through compare) to rank countries on one basis.
How to cite
U.S. Census Bureau. Annual estimates of the resident population for incorporated places, 1 July (Population Estimates Program, subcounty totals). https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-12.Use this data in your AI agent
Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:
What is the latest population in Alton, IL? Cite the source.
get_value {"indicator":"population","place":"us-place-1701114"}
GET https://invokely.ai/api/v1/value?indicator=population&place=us-place-1701114Questions
What is the population in Alton, IL?
Population in Alton, IL was 25,013 in 2025, according to the U.S. Census Bureau. That is down 0.1% from 2024. That is the 90th highest of 225 cities in 2025.
Where does this figure come from?
U.S. Census Bureau. Annual estimates of the resident population for incorporated places, 1 July (Population Estimates Program, subcounty totals). Retrieved by Invokely on 2026-10-12.
What was the highest population in Alton, IL?
25,640 in 2020, the highest value since 2020 in this series.