Groton
- County:
- Brown County
- County Seat:
- No
- Area (mi²):
- 1.751
- State:
- South Dakota
Groton is a city located in Brown County, South Dakota. Groton has a 2026 population of 1,343. Groton is currently declining at a rate of -0.67% annually and its population has decreased by -2.75% since the most recent census, which recorded a population of 1,381 in 2020.