Grande Ronde Valley in La Grande
La Grande sits on the western edge of the Grande Ronde Valley. This page uses reference and county sources.
The valley
Wikipedia describes the Grande Ronde Valley as about 35 miles long north to south and 15 miles wide east to west, with a valley floor near 2,700 feet. It is bounded by the Blue Mountains and the Wallowa Mountains and drained by the Grande Ronde River. Mount Fanny, on the east side, is listed at 7,136 feet. The communities in the valley are La Grande, Cove, Imbler, Island City, Summerville and Union.
A short history
Wikipedia reports that the Astor Expedition passed through in 1811 and that the valley was a waypoint on the Oregon Trail. Benjamin Brown founded the first permanent settlement in 1861. The town was renamed La Grande because another Brownsville already existed in Linn County, and the name is said to mean "great circle." The city was incorporated in 1865.
Union County
Union County's own history page says the county was created on October 14, 1864, from Baker County. The seat moved between Union and La Grande several times and was permanently transferred to La Grande in 1905. The page says the first economic interest was mining, later replaced by farming, cattle, sheep raising and timber. The Union County site carries county government information, including the board of commissioners.