Castle Rock
- County:
- Cowlitz County
- County Seat:
- No
- Area (mi²):
- 2.095
- State:
- Washington
Castle Rock is a city located in Cowlitz County, Washington. Castle Rock has a 2026 population of 2,445. Castle Rock is currently growing at a rate of 0.12% annually but its population has decreased by -0.24% since the most recent census, which recorded a population of 2,451 in 2020.