Originally in 1878 and 1879 the railroad was the Oregon Steam Navigation Company. In the late 1880's Union Pacific purchased half of the company, with ties of Northern Pacific. The new branch to Spokane arrived in that city in 1889. As time went on, the O-WR&N name slowly fell into disuse. Although in lateer years, steam locomotives still carried that name, the tenders of the locomotives had the Union Pacifc emblem on them. All diesel locomotives came letteed and painted in Union Pacific colors, and therefore the Oregon-Washington Railroad & Navigation company name became much less visible as time went on.

Although corporate existance of the O-WR&N would continue afterward, for practical purposes of this brief history, the Union Pacific will be considered to have become the successor of the O-WR&N around 1950.