| Grande Ronde Valley | |
|---|---|
 Elevation map of Union County, with the Grande Ronde Valley featured in the center. | |
| Floor elevation | 820 m (2,690 ft) |
| Length | 35 miles North to South |
| Width | 15 miles |
| Geology | |
| Type | Flood basalt |
| Geography | |
| Location | Union County, Oregon, United States |
| Borders on | Blue Mountains |
| Rivers | Grand Ronde River |
The Grande Ronde Valley is a valley in Union County in northeastern Oregon, United States. It is surrounded by the Blue Mountains and Wallowa Mountains, and is drained by the Grande Ronde River. La Grande is its largest community. The valley is 35 miles (56 km) long, north to south, from Pumpkin Ridge to Pyles Canyon, and 15 miles (24 km) wide, east to west, from Cove to the Grande Ronde River's canyon. Its name, fittingly, means, "great circle."