Plum
- County:
- Allegheny County
- County Seat:
- No
- Area (mi²):
- 28.57
- State:
- Pennsylvania
Plum is a borough located in Allegheny County, Pennsylvania. Plum has a 2026 population of 26,420. Plum is currently declining at a rate of -0.28% annually and its population has decreased by -2.65% since the most recent census, which recorded a population of 27,140 in 2020.