Trains on the Sunset Route of the Southern Pacific lines have crossed the Pecos River on three different bridges, completed in 1883, 1892, and 1944. The most famous was the 1892 Pecos High Bridge, for many years the highest railroad bridge in North America. On the original Sunset Route, completed in 1883, a low bridge was located at the mouth of the Pecos River, where it joins the Rio Grande. To reach this crossing, trains between Comstock and Langtry had to follow a winding route called the Loop Line, which descended southward down steep grades into the canyons of the Rio Grande, passed through two tunnels and deep cuts, and ran along ledges where the danger of rock slides was constant. In 1892 the Pecos crossing was moved northward five miles upstream from the junction with the Rio Grande, in order to eliminate the Loop Line and shorten the rail distance between San Antonio and El Paso by eleven miles. The new line reached the Pecos at a point where the river flows through a deep gorge. The Pecos High Bridge was built there in only eighty-seven working days, between November 3, 1891, and February 20, 1892. Some colorful legends of Judge Roy Bean date from these days, when he served as coroner after construction accidents. The first train to cross the bridge was a special carrying C. P. Huntington, president of the Southern Pacific, on March 30, 1892.
The 1892 high bridge was built by the Phoenix Bridge Company of Phoenixville, Pennsylvania, and was of the metal viaduct style with cantilever center sections. It was supported by twenty-four towers and had a total length of 2,180 feet. The rails stood 321 feet above the river. The bridge was thus the highest railroad bridge in North America and the third highest in the world (exceeded only by the 401-foot Garabit Viaduct in France, built in 1884, and the 336-foot Loa Viaduct in Bolivia, built in 1889). For many years it was a tradition for trains to pause near the bridge and proceed slowly so that passengers could view the canyon, the landmark bridge, and the river below. In 1909 and 1910 the structure was significantly reinforced, the original four-leg central towers were converted to six-leg towers, and the length was reduced to 1,516 feet by a filled embankment at the west end. Additional reinforcement was added in 1929. Finally, with the increased rail traffic during World War II, it became clear that a new, heavier structure was needed.
Construction was begun in August 1943 at a site 440 feet downstream from the 1892 bridge. The new Pecos High Bridge was designed by Modjeski and Masters of Harrisburg, Pennsylvania, in the continuous cantilever truss style. The tall concrete piers were built by Brown and Root Company. The new bridge had a length of 1,390 feet and carried the rails 322 feet above the river. The Sunset Limited was the first train to cross when the bridge was opened to mainline traffic on December 21, 1944. The 1944 Pecos High Bridge is still in use, but the rails now stand only about 265 feet above the Pecos River, which has risen because of Amistad Reservoir. The 1892 bridge was dismantled in 1949, with sections sold to highway departments and local governments in several states. The abutments are located on private property. The grade of the abandoned Loop Line is visible in Seminole Canyon State Historical Park.