Waterloo
- County:
- Lyon County
- County Seat:
- No
- Area (mi²):
- 59.17
- State:
- Kansas
Waterloo is located in Lyon County, Kansas. Waterloo has a 2025 population of 242 . Waterloo is currently growing at a rate of 1.68% annually and its population has increased by 3.42% since the most recent census, which recorded a population of 234 in 2020.
The median age in Waterloo is 62 years: 61.2 years for males, and 68.7 years for females. For every 100 females there are 157.9 males.