The completion of the main line down the Columbia River left a lot of the area to the south without rail service. The Oregon Railway & Navigation Company initially resisted efforts by the citizens of the bypassed area to build extensions to serve them; however, this resistence quickly faded in the late 1880s with two events. The first was an agreement the citizens of Heppner, OR, reached in 1887 with the Chicago & Northwestern Railroad, which was then contemplating an extention to the northwest, to build a line connecting the town with the Columbia River, provided that the citizens provide a $100,000 subsidy to the C&NW; the second was the discovery of coal fields in the area south of Heppner. To head off the threat of competition the OR&N placed its survey parties in the field by September 1887; the citizens of Heppner agreed to give the railroad station grounds free of charge; and by the end of April 1888 contractors were at work building the grade. The OR&N completed the line into Heppner by late November 1888, and on 26 November the citizens of the town congregated at the depot grounds to meet the arrival of the first train.

The Heppner Branch extended 45 miles south from a connection with the mainline at Heppner Junction to the town of Heppner. Extension of the line beyond Heppner looked likely into the early 1890s, with the most immediate objective being the coal mines south of town. However, in early 1891, the Union Pacific brought in a drilling rig and some coal experts to evaluate the deposits, only to reconfirm earlier findings that the coal beds were very limited.


UP #107 with a freight in Heppner.

Agricultural traffic supported the line through the next several decades. Tragedy struck the line on 14 June 1903, when a flash flood killed 200 people in Heppner and destroyed two miles of the branch; the survivors in Heppner were able to warn the downstream communities of the approaching water and saved many more lives. In 1953, Kinzua Pine Mills completed a large sawmill in the town. Lumber and woodchips from the sawmill then became the largest source of traffic handled over the line.

Operations over the line in the final years of the branch saw trains operating out of The Dalles, OR on Tuesdays and Thursdays. The Heppner local would run 59 miles east on the mainline to Heppner Junction before turning south. However, Kinzua Corp. was not shipping enough traffic to warrant maintaining the line, and in late 1993/early 1994 Union Pacific initiated abandonment proceedings for the line. The last train ran on 30 June 1994 when a light locomotive ran down to retrieve a single empty bulkhead flat from the Kinzua Corp. mill. The branch was officially abandoned and salvaged a short time later, except for the first three quarters of a mile from Heppner Junction that remains in place today and is used only for car storage.