Tualatin Plains | |
|---|---|
Region | |
 The plains south of Hillsboro | |
 | |
| Coordinates: 45°30′38″N 122°59′19″W / 45.51056°N 122.98861°W | |
| Country | United States |
| State | Oregon |
| Region | Washington County |
The Tualatin Plains are a prairie area in central Washington County, Oregon, United States. Located around the Hillsboro and Forest Grove areas, the plains were first inhabited by the Atfalati band of the Kalapuya group of Native Americans. Euro-American settlement began in the 1840s.