Thornton
- County:
- Adams County
- County Seat:
- No
- Area (mi²):
- 36.504
- State:
- Colorado
Thornton is a city located in Adams County, Colorado. Thornton has a 2026 population of 146,689. Thornton is currently growing at a rate of 0.79% annually and its population has increased by 3.16% since the most recent census, which recorded a population of 142,191 in 2020.