Flagtail Mountain is a 6,586-foot summit in Grant County, Oregon, and is notable both for its elevation and its longstanding role in forest fire observation. A lookout was first built there in the 1920s, showing how the mountain served as an important high point for wildfire detection. Additional lookout structures were erected in 1933 and 1960, continuing that function across decades. The mountain’s lookout heritage later received formal recognition in 2003, when the site was entered on the National Historic Lookout Register.