Rochester
- County:
- Sangamon County
- County Seat:
- No
- Area (mi²):
- 2.683
- State:
- Illinois
Rochester is a village located in Sangamon County, Illinois. Rochester has a 2026 population of 4,044. Rochester is currently growing at a rate of 3.19% annually and its population has increased by 4.66% since the most recent census, which recorded a population of 3,864 in 2020.