The West Union area was home to one of the earliest caucasian communities in Washington County. Former Rocky Mountain fur trappers settled on the Tualatin Plains in the early 1840s and gathered regularly at the Five Oaks site. The surrounding region was named West Union because this was the western frontier and was their meeting, or union, place. A post office was established in 1874. Stephen A. Holcomb was the first postmaster and the West Union post office was in his home, near the intersection of Cornelius Pass and West Union Roads. There were ten more postmasters before the post office closed in 1894.
David T. Lenox, captain of the first wagon train to cross the Rockies, and his wife Louisa were the first caucasian settlers in this area. Lenox took up his land claim in 1843 and, in May of 1844, the first meeting of the West Union Baptist Church was held in the Lenox cabin (later, in 1853, Lenox donated land for the construction of a church building). This was the first Baptist church organized west of the Rockies. It isn't the only first associated with West Union, however.
In November of 1851, West Union became the site of the first public school meeting in Oregon when seven pioneers organized School District #1. $500 was raised to build a schoolhouse and, in 1852, it was constructed on Stephen Holcomb's land claim (the site lies about 100 yards south of the intersection of Croeni and Jacobson Roads). The original school was replaced in 1892 and the second building served until the construction of a consolidated school in 1949.