Washington State Route 17 Coulee City–Brewster branch of PSH 10 was codified in 1931 as a branch of State Road 10 and re-codified in 1937, during the creation of the primary and secondary state highways; however, the highway was not built between Sims Corner and Bridgeport until the 1950s. The Soap Lake–Coulee City branch of PSH 7 was established in 1937 to serve as an alternate route to SSH 2F, avoiding the Grand Coulee Dam. In 1951, the PSH 10 branch between Bridgeport and Brewster was moved north of the Columbia River via the newly built Columbia River Bridge on the present route of
Birch Coulee Battlefield edge is a steep wooded ravine, a landform known locally by the French term "coulee," also spelled "coulie" or "cooley." Birch Coulee, known to the Dakota as "Tanpa Yukan" (Place of the White Birch), is deep and runs for a total of down to the Minnesota River. A few hundred yards to the west of the coulee, the prairie rises slightly onto a gentle knoll. On September 1, 1862, a burial detail of about 170 Union Army volunteers and civilians under Major Joseph R. Brown camped on the prairie west of Birch Coulee. The site was selected by Captain Hiram