Francis A. Chenoweth operated a rail line on the river's north bank in present-day Washington in 1851.

[10][11] In 1861, John W. Brazee of the Oregon Portage Company started to build a 5 ft (1,524 mm) broad gauge railroad out of a mule-and-wagon road that had been constructed by Col. Joseph S. Ruckle and Harrison Olmstead in 1856 but had been out of service since around 1858.

Brazee's conversion of the road cost $50,000 USD (equivalent to $1,695,556 in 2023), and the line opened on 20 May 1861, still relying on mule power.

[8][9][12] After one more year, the portage company acquired the Oregon Pony, which became the first locomotive in the Pacific Northwest,[1][13] debuting for the railroad on 10 May 1862.

[1][6] Restoration of the railroad in 1891, including a conversion to the 3 ft (914 mm) narrow gauge, was a result of demands from steamboat captains and delays in the construction of the Cascades Locks and Canal.