The Sunset Route's western terminus officially begins about 71 miles (115 km) east of Los Angeles, in West Colton, California. Going eastward, the route immediately faces steep inclines of up to 1.9% as it reaches 2,560 feet (780 m) in elevation at Beaumont Hill, near Palm Springs, California. It then turns southeast, quickly dropping to 201 feet (61 m) below sea level at Wister, California on the landlocked Salton Sea. The route rises to 385 feet (117 m) in elevation before dropping again as it goes through Yuma, Arizona, near the California and Mexico borders and close to where the Gila River discharges into the Colorado River. It turns directly east to Maricopa, Arizona, at the southern edge of the Phoenix metropolitan area, before turning to the southeast again to Tucson, Arizona. Heading eastward again, the route rises to 4,557 feet (1,389 m) at Dragoon in southeast Arizona, drops to 3,600 feet (1,100 m) in San Simon, Arizona, and then crosses the Continental Divide at 4,554 feet (1,388 m) elevation at Wilna in southwest New Mexico before crossing into Texas at the Mexican border metropolis of El Paso.[4][5] The Sunset Route is the lowest railway that crosses the Continental Divide.[6]
The line is primarily used for freight by the Union Pacific. BNSF shares ownership of the Lafayette Subdivision.[8]
In 1998, the Los Angeles-El Paso section of the Sunset Route was hosting about 33 trains per day.[9] By 2007, 45 trains daily were operating through Maricopa, Arizona,[10] 55 daily trains were running in 2015, and 90 were projected after the full completion of the second track on the Los Angeles-El Paso section.[11] However, by 2019 the number of daily trains between Los Angeles and El Paso had dropped to 39, and the section east of El Paso in the Trans-Pecos region was hosting 12 trains per day.[9] In June 2024, the daily traffic in Wellton, Arizona was 28 trains (14 in each direction), of which a majority were intermodal freight trains, about a quarter were mixed freight trains, and 6% carried automobiles. The reduced number of trains were somewhat offset by increasingly large train lengths; several of the longest trains observed were at least 18,000 feet (5,500 m) in length.[12]
When Southern Pacific Railroad merged with Union Pacific in 1996, the operating plan that was filed along with the merger application stipulated that one of the first major investments would be to double-track the Sunset Route between Los Angeles and El Paso.[14] At the time of the merger, only about 152 miles (245 km), or approximately 20% of the route, were double-tracked.[4][15] However, the combined company's efforts to expand double-trackage between Los Angeles and El Paso were soon delayed in favor of more profitable investments on Union Pacific's pre-existing lines north of the Sunset Route to improve coal-hauling capacity or to better handle mixed-freight trains along the Central Corridor.[14]
Work to add the second track picked up in the mid-2000s,[10][16] and by late 2007, Union Pacific was targeting the complete double-tracking of the 757-mile (1,218 km) Los Angeles-El Paso section by the end of 2010.[17][18] By 2012, 72% of that section, or 547 miles (880 km), would have two tracks, including the entire section between Tucson and El Paso. Union Pacific no longer provided a specific timeline for full completion of the second track, though.[19] As of 2015[update], the double-tracking project reached 80% completion.[11] In 2024, Union Pacific announced the resumption of work to add the second main line on the remaining 127 miles (204 km) of single-track railway.[20][21]
