John Day
- County:
- Grant County
- County Seat:
- No
- Area (mi²):
- 2.26
- State:
- Oregon
John Day is a city located in Grant County, Oregon. John Day has a 2026 population of 1,641. John Day is currently declining at a rate of -1.8% annually and its population has decreased by -2.09% since the most recent census, which recorded a population of 1,676 in 2020.