The plan for the bridge was approved May 25, 1903. A contract was let to the Phoenix Bridge Company and work got under way. Since the U. S. Corps of Engineers determined that the White River was a navigable waterway, a turn span had to be introduced to permit steamboats free progress up the river. The turn span was 285 feet long and the elevation from the top of the rail on the span to low water level was 59 feet (which was 410 feet above sea level). The bridge was designed to handle a 35 foot rise which would give a plus or minus 15 foot clearance from high water. The total length of the bridge, not including the short five panel timber trestle approaches at each end, was 1091 feet, 7½ inches. The grade from milepost 381.8, just north of the final location of the Cotter depot, to the first masonry pier was ascending at 1%. The first three steel deck girder spans were level, the turn span and next girder span were level, while the last six deck girder spans started climbing and elevated the grade two plus feet in 320 feet. The total length of each deck girder spans was 80 feet 3½ inches.The grade then returned to a steady 1% up through the tunnel (roughly 1000 feet past the bridge) and continued to milepost 391.6. Since the bulk of the bridge was brought in by steamboat and barge, there was no need to wait for the completion of the railroad to Cotter to commence construction. By June 1904, trains began operating over the bridge, but the turn span was not completed until June 20. The turn span was operated just once, for testing and acceptance by the railroad, and never turned again. The arrival of the railroad in Cotter killed off the steamboat business.

This bridge was built by the White River Railway (the construction company) for the Saint Louis Iron Mountain & Southern Railway, later owned by the MP, then conveyed to the UP in the 1984 merger, and became the property of the newly formed Missouri and North Arkansas Railroad (MNA) in 1992.

Threre appears to be a conflict between the photo date and the upgrade date, and I will research that, but I stand by the photo date based on the Kodak date stamp and the pencil notations on the slide frame.

This unit and one B unit were equipped with 12-cylinder Cooper-Bessemer FVBL-12 diesel prime movers (these two were informally known as Model UM-16, 1600 hp), while the other A-B units were equipped with 8-cylinder C-B FVBL-8 diesels (informally known as UM-12 for the 1200 hp they produced). The purpose was to test existing designs in road locomotives. Alco had upset GE by not bidding on a couple of locomotive contracts that GE was interested in, so GE set out on its own to build a road diesel, which in the long run proved fatal to Alco. From 1954-1959, the UM-20 (also known as UM-20B) tested on the Erie, painted in Erie colors and numbered #750A-B-C-D. Since GE's design department had a hand in locomotive designs at Alco, there is a similarity between this design and the FA-1/FA-2 Alcos. These locomotives lead to the design and development of the U25B. After the Erie road tests, the locomotives were returned to GE, where all four units were upgraded to 2000 horsepower locomotives with 12-cylinder C-B FVB12LT diesel prime movers, and sold to the UP on October 21, 1959 as #'s 620-620B-621B-621. They were retired by the UP in 1963 and traded to GE on U50's.