The Oregon Central Rail Road was the name of two railroad companies in the U.S. state of Oregon, each of which claimed federal land grants that had been assigned to the state in 1866 to assist in building a line from Portland south into California. The "East Side Company" of Salem (incorporated 1867), supported by businessman Ben Holladay, eventually received the grant for its line east of the Willamette River, and was reorganized in 1870 as the Oregon and California Railroad (O&C), which completed the line in 1887. Portland supported the competing "West Side Company" (incorporated 1866), which only built to McMinnville, and was sold to the O&C in 1880. The O&C was later acquired by the Southern Pacific Company, and mostly remains as part of the Union Pacific Railroad's I-5 Corridor; the West Side line is now operated by the Portland and Western Railroad between Beaverton and Forest Grove.
An early version of the Pacific Railway Act of 1862 included a branch north into Oregon, but this was left out of the law as passed. In its place, an 1866 law gave land grants to California and Oregon to convey to the California and Oregon Railroad of California and a company to be designated by the Oregon Legislature that would build the line. Led by Joseph P. Gaston, railroad promoters informally organized the Oregon Central Railroad (West Side Company) on October 6, and the legislature designated this company, which did not file incorporation papers until November 21, as the beneficiary of the federal grants four days later. The company adopted a line surveyed in 1864, which would begin at Portland (then entirely on the west side of the Willamette). In July 1865, Californians associated with the California and Oregon Railroad incorporated the first Oregon and California Railroad, but failed to acquire control of the West Side Company. Undaunted, they incorporated a second Oregon Central Rail Road (East Side Company) in April 1867, with Governor George L. Woods as president. The West Side Company broke ground in Portland on April 15, 1868, and the East Side Company followed suit the next day in East Portland.