Union Gap
- County:
- Kittitas County
- County Seat:
- No
- Area (mi²):
- 5.577
- State:
- Washington
Union Gap is a city located in Kittitas County, Washington. Union Gap has a 2026 population of 6,582. Union Gap is currently declining at a rate of -0.05% annually but its population has increased by 0.44% since the most recent census, which recorded a population of 6,553 in 2020.