St. John
- County:
- Whitman County
- County Seat:
- No
- Area (mi²):
- 0.671
- State:
- Washington
St. John is a town located in Whitman County, Washington. St. John has a 2026 population of 590. St. John is currently growing at a rate of 1.55% annually but its population has decreased by -1.17% since the most recent census, which recorded a population of 597 in 2020.