The line was originally called the Guymard Cutoff. The Erie's chief engineer, James Graham, died in February 1909, a month after the line was fully opened to traffic. By 1911, the Guymard station was renamed Graham and the cutoff became the Graham Line. In both cases, the cutoff was named for the little-known station at its west end, where it joins the original Main Line on the grade down to Port Jervis. In a lawsuit of this same period, the owners of the Guymard Lead and Zinc Mine, inactive since 1876, sued the Erie for building a "spur" line that blocked their access, which may have influenced the Erie to change the name.

The short section from Newburgh Junction (on the Main Line at Harriman) to Highland Mills was part of the Erie's original Newburgh Branch, opened in 1869, but it was considered part of the Graham Line after that branch closed to passenger service in 1935.^[1][2] The old Main Line was abandoned in 1954 west of Howells, where the two lines came side by side, and after that date the Graham Line was considered to end at Howells Junction.

Passenger rail service edit

Effective April 18, 1983, Metro-North Railroad shifted its Port Jervis Line service to run on the Graham Line, marking the first time it had hosted scheduled passenger service. The line also got its first passenger stations, at Salisbury Mills-Cornwall, Campbell Hall, and Middletown (which is not actually in Middletown but nearby). Following the Metro-North change and discontinuance of its own local freight service, Conrail, owner of the railroad, was able to abandon the original Main Line the following year. Using the Graham Line avoided the many grade crossings in the old town centers, improving safety and train speed. But the Graham Line, designed entirely for freight trains, has the disadvantage for passenger services of running through much less-populated areas. Commuters arrive at the Graham Line stations almost entirely by automobile.