[1] The 11 miles (18 km) of the Albany-Lebanon mainline were built by the newly founded Albany and Lebanon Railroad in 1880.

The A&L was shortly thereafter bought by the Oregon and California Railroad, which ran from Portland to the Oregon-California border.

New branches were also constructed as the Willamette Valley industrialized, including a 36 miles (58 km) route northeast from Lebanon to the booming lumber town of Mill City built in 1910.

SP leased both branch lines to the Willamette Valley Railway in 1993, and sold them outright to WVR in 1996 shortly before its acquisition by Union Pacific.

Five years later, in 2003, AERC bought the Albany-Lebanon and Lebanon-Mill City lines from WVR, completing the current network.