The Eastside Railway Company was a fifteen-mile line that operated from Portland to Oregon City. It was built in 1893 and is believed to be the first interurban railroad line in the United States to use electricity that was generated by water power. Originally an interurban, the line was almost entirely passenger traffic during its first decade.

It was sold to a number of different companies during its existence. The first was the Oregon Water Power & Railway. Then it was soon sold to the Portland Railway Light and Power Company. Then lastly, the Portland Traction Company. The latter operated it for many years as a freight operation, using traffic generated in Milwaukie and interchanging with the SP in Oregon City. It was sold to Union Pacific in the 1980s, who retained ownership of the property, but removed the ties and rails around 1993.

Today, much of the line is visible. The old bridge over the Clakamas River is still intact except for its eastern approach. In unincorporated Oak Grove, the line is very visible as it is the grassy divider in the middle of the main road. Portland Metro purchased the property from Union Pacific in 2001 with hopes that in the future it could be developed into a trail.

Towns along the line were Portland, Milwaukie, Oak Grove, Gladstone, and Oregon City.