The Sunset Route is divided into the following subdivisions:
Yuma subdivision from West Colton (CP Rancho) to Yuma, AZ
Gila subdivision from Yuma to Tucson
Mileposts are from San Francisco. Dispatching in Southern California is carried out from a joint UP/BNSF Dispatching Center in San Bernardino, CA. The line is Two Main Tracks, CTC and the speed limit is 50 mph, at Indio Yard (MP 611.3), which once a major SP sorting facility, that was substantially downgraded once the West Colton Yard opened, and now is almost non-existent. The line, below sea level at this point, turns south-southeast as it passes the yard, on the east side of the line, ending at East Indio (MP 612.3), with Intermediate Signals at MP 613.9, short extra tracks on each side at the crossovers at Coachella (MP 615.0), where the speed limit rises to 70-50. There is a road bridge overhead, the road to Niland is alongside to the southwest, there is a grade crossing, an angled grade crossing, and another grade crossing, with Intermediate Signals at MP 615.4/5 and MP 617.0, a bridge across Whitewater Creek, and a grade crossing, and the line becoming single-track CTC at Thermal (CPSP 620, MP 620.2), where the speed limit is 65-60 before rising to 79-70
There are Intermediate Signals at the former location of a detector at MP 621.4, a grade crossing, dual highway bridges overhead, the road still alongside to the southwest, Intermediate Signals at MP 623.2, and a grade crossing. There is an 8,388 ft. siding on the north side at Mecca (MP 624.6-626.1), and the line turns southeast within the siding to begin the series of diversions around the Salton Sea.
Along here, the track is almost a hundred feet below sea level, but when it was built it had been almost three hundred feet below sea level, at the bottom of the Salton Sink that was then completely dry. The present body of water was created in the first few years of the twentieth century, when a flooding Colorado River burst through the control gates at the irrigation outlet, and the flood water poured downgrade to the Salton Sink. Over the next several years, numerous attempts to close the breach in the Colorado's flood walls were unsuccessful, and the level of the new Salton Sea continued to rise. As it did so, it began to cover the lines of the Southern Pacific, which was forced to lay a new line higher up. Several years later, when forced to move the line for the third time (to its present location), the SP's management had had enough, and the railroad took on the challenge of sealing the breach. With all of the engineering resources of the railroad at its disposal, it was successful where others had not been, and the breach was closed. In the ninety plus years since then, evaporation has reduced the level of the “sea” so that in most places it no longer washes adjacent to the tracks, and in so doing has raised the salinity of the water well above that of the Pacific Ocean, just 200 miles away.
There is a detector at MP 627.0, a grade crossing, a road alongside to the east, the line turns east, past Intermediate Signals at MP 631.6, and then south-southeast again as the speed limit falls to 75 mph at the 8,483 ft. north side siding at Mortmar (MP 632.9-634.6), along the northeast shore of the Salton Sea, and the line continues along that shore past Salton (CP SP 637, MP 636.6), a new section of Two Main Tracks, CTC, initiated in December 2012, encompassing the former 8,269 ft. siding on the south side at Ferrum (MP 638.9-640.6), where Kaiser Steel's line to Eagle Mountain once headed east (and there is still a wye on the north side), and a bridge over an arroyo, a speed limit rise to 79-75, Durmid, a detector at MP 643.8, Intermediate Signals at MP 644.8, and the former 8,372 ft. SW side siding at Bertram (MP 646.1-647.8), where the new stretch of 2MT ends, a short spur on the SW side near the west end of the siding, a dirt road grade crossing at station name Bertram, a turn to the northeast, just east of the siding, onto an additional diversion as the water level rose, Intermediate Signals at MP 650.x, the former location of a detector at MP 650.1, a turn southeast, Intermediate Signals (MP 652.x) at a grade crossing near the east end of the turn, and the former location of a detector at MP 652.4, to the 8,387 ft. siding on the north side at Rogoza (MP 654.4 to 656.1), where the speed limit falls to 70 mph. There is an agricultural inspection station on the roadside southwest of the line near station sign Rogoza.
The countryside along here is Sonoran Desert—sagebrush scrub in the sand, but no cacti. The line turns south-southeast again, past a detector at MP 657.2, a bridge over an arroyo, Intermediate Signals at MP 658.6, five bridges over arroyos, the 8,333 ft. siding on the north side at Wister (MP 659.8-661.5), five bridges over arroyos within the siding, three bridges over arroyos east of the siding, a dirt road grade crossing, a detector at MP 662.5, four more bridges over arroyos, and Intermediate Signals at MP 662.8, before turning east-southeast and leaving the Salton Sea behind. There is a bridge over an arroyo, Intermediate Signals at MP 664.4, a bridge over an arroyo, a grade crossing, and two more bridges over arroyos.
At Niland, a 12,169 ft. siding on the north side begins at MP 665.6, as does an 8,548 ft. siding on the south side. There are five more bridges over arroyos and two extra tracks on the south side, the line south to El Centro departs at MP 667.3, where the south side siding ends, there are crossovers between the main and the north siding, with a bracket signal west of the crossovers and a signal bridge east of them, there is an east leg of the wye with the El Centro line, a grade crossing passing through the middle of the wye, and the north side siding and the east leg of the wye end at MP 667.8 and 667.9 (East Niland).
The main line continues past three bridges over culverts, Intermediate Signals at Flowing Well (MP 669.3), a bridge over a culvert, Intermediate Signals at MP 670.3, a detector at MP 670.5, where it reaches sea-level (heading upwards) and climbs above it again, a bridge over a culvert, a dirt road grade crossing, two bridges over culverts, an 8,475 ft. north side siding at Iris (MP 673.9-675.6), where the speed limit rises to 79-75, with a bridge over a culvert within the siding, a bridge? over the Coachella Canal, a dirt road grade crossing, Intermediate Signals at MP 676.9, a bridge over a culvert, Intermediate Signals at the former location of a detector at MP 678.0, four bridges over culverts in an embankment, Intermediate Signals at MP 679.9, a turn to the southeast, the 8,472 ft. north side siding at Regina (MP 681.2-682.9), trees as a wind barrier, Intermediate Signals at Amos, three bridges over culverts, a detector at MP 685.9, nine bridges over culverts, the 8,495 ft. north side siding at Acolita (MP 688.8-690.5), with six bridges over culverts within the siding, and nine bridges over culverts.
There are Intermediate Signals at MP 691.9, seventeen bridges over culverts, the former location of a detector at the Intermediate Signals at MP 693.8, three bridges over culverts, the Imperial Dunes National Monument off to the south, the 8,486 ft. south side siding at Glamis (MP 697.1-698.7), where the Mesquite Line, opened in June 2012, diverges CP SP 697) to serve a landfill, with two bridges over culverts, a grade crossing, and a bridge over a culvert within the siding, a bridge over a culvert, Intermediate Signals, a bridge over a culvert, MP 700, a bridge over a culvert, a detector at MP 700.4, a bridge over a culvert, MP 701, two bridges over culverts, Intermediate Signals at Rutheen (MP 701.9), six bridges over culverts, Intermediate Signals, two bridges over culverts, the 8,500 ft. north side siding at Clyde (MP 704.9-706.6), with four bridges over culverts within the siding, three bridges over culverts, Intermediate Signals, a bridge over a culvert, Intermediate Signals, three bridges over culverts, Intermediate Signals, a detector at MP 710.7, and a bridge over a culvert.
The Intermediate Signals along here are individual searchlights, arranged on opposite sides of the single track, which passes the 8,422 ft. north side siding at Cactus (MP 711.9-713.6), with a grade crossing and seven bridges over culverts within the siding, four bridges over culverts, Intermediate Signals at the former location of a detector at MP 715.0, six bridges over culverts, Intermediate Signals at Ogilby (MP 716.6), three bridges over culverts, Intermediate Signals, two bridges over culverts, the 8,406 ft. north side siding in the sand at Dunes (MP 719.9-721.6), where the speed limit falls to 79-60, a bridge over a culvert, Intermediate Signals and a detector in the sand at MP 722.5, a dirt road grade crossing, and a detector at MP 723.7, where the speed limit falls to to 50 mph, and the line turns due east, past Intermediate Signals at MP 723.x, a bridge over an arroyo, a road alongside to the south, and I-8 beyond the road, and then east-southeast.
The speed limit falls to 40 mph, and Two Main Tracks, CTC, start at Araz (MP 725.8), before bridging across the All-American Canal on a deck concrete bridge, where the Inter-California Railroad once trailed in from the south-southwest, and rises to 60-50 as the line turns east-northeast, past a dirt road grade crossing with I-8 alongside to the south, to clear a bend of the Colorado River, past El Rio, a bridge over a culvert and MP 727, and then turns east-southeast past broken land on either side, a bridge over a road, signal bridges and crossovers at Winterhaven X-over (MP 729.1), with the line up on a bridge or embankment, a bridge over a road, the former location of a detector at MP 729.9, where it turns southeast, a grade crossing, a bridge over a road, to Colorado, CA (MP 732.1), with an old depot on the south side, inside the curve, and a street alongside to the south, where a branch from Imperial Dam once trailed in from the north.
The line turns south-southeast, single track, past a road bridge overhead, across the through girder bridge over the Colorado River and entering Arizona, with a street alongside to the west, a road bridge overhead, and extra track on the west side, into Yuma, AZ (MP 732.4), where the speed limit is 25 mph, the line becomes Double Track, with the west/south track in Yard Limits and the East/North Track ABS, and there is an Amtrak station on the west side of the line (with a west-facing stub track on the west side of the platform, a platform on the west side of the tracks, a platform between tracks, and a depot on the west side, west of the west-side platform), with a bridge over a divided street at the south end of the station and Intermediate Signals at MP 733.1. The line turns east-southeast, with two extra yard tracks on the west/south side, at Subway (MP 734.0), where there are crossovers with the yard tracks beginning on the south side, initially four yard tracks, a road bridge overhead, three yard tracks plus others going to a freight car repair shop, tracks on the south side trailing in from industries, a yard track becoming two tracks serving industry on the south side, a spur once trailed in on the south side, a road bridge overhead, crossovers between a yard track and the south track (eastbound line), two yard tracks near the main lines on the south side, grain silos on the south side, served by 'yard' tracks south of the pair near the main line, a spur trailing into the south yard track from a petrochemical facility, a road bridge overhead, a spur trailing in from the south to the southernmost yard track, and the yard tracks reducing to just two widely-spaced tracks, a spur trailing in on the south side, a spur serving a petrochemical facility on the south side, and the end of double track at East Yard (MP 737.5), where the yard on the south side of the line ends, the speed limit rises to 50 mph, and the line turns east.
Now in the valley of the Gila River, in the Sonoran Desert, the line becomes single track, CTC, with speed limit 79-70, as it heads east past Intermediate Signals at Araby (MP 738.7), a detector at MP 740.2, a bridge over a street, a spur into industry on the south side, dual road bridges overhead, a grade crossing, what was formerly (until 2006) the 8,388 ft. siding at Fortuna (MP 742.8-744.6), where the speed limit falls to 70 mph and the line turns northeast, and is now a stretch of Two Main Tracks past Intermediate Signals at Parker (MP 744.6) and a grade crossing, to the current end of 2MT, and former Intermediate Signals, at Blaisdell (MP 746.6), where the line turns north, past a spur trailing in from the south and extra track on the south side, and then northeast along the south bank of the Gila River.
There is a bridge over drainage, a dirt road grade crossing into a granite quarry on the south side of the line, a bridge over drainage, the 8,487 ft. north side siding at Kinter (MP 749.4-751.2), with a bridge over drainage within the siding, where the line turns curvily east on embankment and the speed limit falls to 40 mph, a bridge over a dirt road, a bridges over drainage, a detector at MP 752.5, two bridges over drainage with MP 753 between them, signals at Dome (MP 753.2), where Two Main Tracks start, the line turns south, and the speed limit rises to 60-55, a bridge over drainage, MP 754, two bridges over drainage, MP 755, two bridges over drainage, a bridge over an arroyo, a bridge over drainage, Intermediate Signals at MP 756.1, two bridges over drainage, MP 757, a bridge over drainage, Intermediate Signals at MP 757.5, Granite Spur, where the line turns southeast, three bridges over drainage, detectors at MP 758.2, two bridges over drainage, Intermediate Signals, a bridge over a dirt road, Intermediate Signals at Ligurta, after which the line turns east and the speed limit rises to 70 mph, a bridge over a road, a bridge over an arroyo with the line on embankment, a bridge over a canal, Intermediate Signals, a dirt road grade crossing, a bridge over an arroyo, two bridges over drainage, Intermediate Signals at Adonde (MP 754.5), two bridges over drainage, a grade crossing, crossovers at West Wellton (MP 768.1), a grade crossing, a bridge over drainage, and a signal bridge, the crossovers (ending the 2MT) and junction at Wellton (MP 770.8), where the little-used (and embargoed, in 2006/7 and earlier) Phoenix line heads away northeast while the main line continues east-northeast, returning to single track, CTC, with a speed limit of 79-70.