There are only two feasible railroad routes north from the Los Angeles Basin to the Mojave Desert—Soledad Canyon from Saugus to Palmdale and Cajon Pass from San Bernardino to Victorville. Southern Pacific used the Soledad Canyon route for its 1870s entry to Los Angeles from the north. When Santa Fe interests needed a way into the Los Angeles basin from the Barstow area in the 1880s, Cajon Pass was selected, not only because the Soledad Canyon route was already taken, but also because the first line projected south from Barstow was headed for San Diego (as the “California Southern”), not Los Angeles. The lines towards Los Angeles were built later and the original line to San Diego abandoned after several washouts in Temecula Canyon a few years after that.
Cajon Pass exists because the San Andreas earthquake fault runs east-southeast to west-northwest through this area (and is also responsible for the pass through Beaumont and Banning to the east). The fault passes just to the north of San Bernardino (at the base of the San Bernardino Mountains), and the resulting cleft in the mountains (between the San Bernardino Mountains to the east and the San Gabriel Mountains to the west) runs in a northwesterly direction from San Bernardino until it reaches the 3000 ft. level, at which the route to the summit turns north and then east in a vast bowl among mountain peaks in all directions. Cajon Creek runs along the bottom of the northwesterly cleft in the lower regions of the pass. In 1950, the BNSF (ex-Santa Fe) tracks were joined by US 66 in traversing Cajon Pass.
The former Santa Fe line over Cajon Pass comprises the following subdivision:
· Los Angeles Division, First District from San Bernardino to Barstow (mileposts from Barstow)
Cajon Pass starts where the route to Los Angeles via Pasadena and the route to Los Angeles via Fullerton come together, just west of the San Bernardino passenger station at milepost 81.4 (from Barstow), 1,040 ft. above sea level. The Santa Fe maintenance shops are to the north of the tracks at this point. on the east side of where Mount Vernon Avenue crosses the tracks on a stylish concrete viaduct. Under the viaduct, an additional track from the Fullerton direction, known as the “short way”, joins from the south. The Santa Fe depot building is on the south side of the tracks, with a number of concrete platforms and platform tracks. There are two main tracks, operated according to Rule 251 on the Automatic Block System and issued Train Orders by a Dispatcher located in the depot in San Bernardino, all the way up the pass from San Bernardino to Summit and down the eastern slop to Barstow. In the immediate vicinity of , there are actually three main tracks, all of them automatic block signaled for current of traffic operations (left-hand running all the way from San Bernardino to Thorn on the east side of the pass). Track speed at San Bernardino is 30 mph for all trains. On the uphill track, from signal 782 west of Highland Junction to signal 572-A west of summit, inclusive, there is a special signaling rule: yellow blocks ('restricted speed') are the most restrictive to avoid stopping trains on the grade. Uphill trains are permitted to close up behind the train in front, on a see-and-be-seen basis. If necessary, a train can close up completely and help shove a stalled train.
At the east end of the San Bernardino Passenger station, following a junction with the line to Redlands, the main line makes a sharp turn to the north, passing over a number of streets at grade (5th street, etc.—the overbridges started to be built in 1951) and passing through the connections to/from the shops. The entire station area, and the exits from the shops, are controlled by the four-storey tower on the west side of the line at Fifth Street (MP 80.8), where yard limits end. There is a signal bridge containing the necessary signal for eastward movement adjacent to the Fifth Street Tower. At Highland Junction, MP 79.4, where there was once a tower (until 1925) controlling the junction and the erstwhile end of double track (which lasted only until 1912) the line to Highland and thence around the loop to Redlands continues north for a short distance, while the main line turns north northwest, and shortly thereafter comes alongside Cajon Boulevard (west of the tracks) and crosses Highland Avenue. There are spurs, closed on September 24, 1950, for Western Stove Company at MP 77.1 and Zeolite at MP 76.7
There is a grade crossing at north-south State Street, followed by the crossovers and sidings on both sides of the track at Ono (MP 76.0). The eastward siding at Ono has a capacity of 106 cars, while the westward siding has a capacity of 96 cars. The tracks continue straight and even, although on a steady upgrade, past the former location—office closed 1899, removed 1905—of a train order office at Verdemont (MP 73.9), before curving northwest and crossing Cajon Boulevard on a road underbridge. There was once a depot—built 1908, closed 1928, retired 1948, demolished 1949—at , where there are crossovers and sidings (128 car capacity eastward, 126 westward). The line then continues north northwest across Devore Road on a grade crossing at MP 71.0, curves to the left across Cajon Creek and then right and again heads north.. At this point, the tracks are on the western edge of the narrowing valley, curving back and forth following the contour of the land. Cajon Creek is in the middle with Route 66 to its east, the creek, and the tracks, which are now climbing more steeply than before. At , the tracks pass a spur at MP 67.3 (a set out track), swing left and reach the eastbound watering station at MP 66.3 which has a depot and several other buildings, crossovers, and an eastward siding with 115 car capacity. The tracks then follow the west side of Cajon Creek around to the east-northeast to Blue Cut, MP 65.0, where the tracks, creek, and Route 66 are very close together. The tracks cross a bridge/culvert over the outlet from Lost Lake, and then curve to the north through the Swarthout Canyon Road grade crossing, following the hillside (but not the main valley side, which is further west) along the creek to Cajon, MP 62.8, where there is a depot and other buildings on the west side of the tracks, watering facilities, another set of crossovers between the two main tracks, sidings for 70 cars eastward and 95 cars westward, and a bridge crossing Cajon Creek.
North of Cajon, the two main tracks separate, with track 2 (the original 1880s track) climbing at a ruling gradient of 3% more directly towards the summit, and track 1 (the later track, built some 25 years after the original line when the Salt Lake Route gained its trackage rights, with a ruling gradient of only 2.2%) swinging away to the west, curving around to the west southwest, crossing Cajon Creek on a curved bridge in the process, and crossing two dirt roads, before reaching the famed Sullivan’s Curve (named after photographer Herb Sullivan, apparently named by Chard Walker in the 1950s). This location is named after a well-known photographer of the steam era in the 1930s, who took many photographs at this location. Beyond Sullivan’s Curve, the track heads northeast for a short distance, then northwest again before curving north to cross Route 138 at grade, crossing Cajon Creek again on a girder bridge and passing the Mormon Rocks outcropping.
After again curving northwest, the line enters a sweeping curve to the east across a bowl at the upper end of the valley, crosses a dirt road near the former location of Pine Lodge (MP 62.0X, with the X denoting that this is on an alternate routing from the original milepost sequence on track 2), and curves east again to reach Alray (MP 59.7X), where there is a 118-car siding. From trackside at Alray, it is possible to look back down the valley and see trains on track 1 just south of the Route 138 crossings. Here, track 1 crosses over Route 66 with a girder bridge onto an embankment leading into a cutting that leads to the only two tunnels on Cajon Pass, 457.5 ft. tunnel 2 at MP 59.18X and 380 ft. tunnel 1 at MP 58.86X. The track is now in another bowl, east of the first one, which leads all the way to the final approach to Summit. At MP 57.2, a concrete bridge crosses another dirt road, and the line then curves around to the south, hugging the edge of the bowl. On the eastern edge of the bowl, track 2 rejoins track 1, and the tracks curve eastward together through a cut, then northeastward past the wye on the south side of the tracks and eastward again to reach the summit of Cajon Pass at MP 55.9 and an altitude of 3811 ft. (2750 ft. above San Bernardino, approximately 25 track miles away).
Meanwhile, track 2 also crosses Cajon Creek on a bridge with somewhat less curvature than track 1, heads northwest for a short distance alongside and just below I-15, and then heads north northwest until it has crossed Route 138 before turning directly east, as it again crosses Cajon Creek with a girder bridge adjacent to some intermediate signals. The track passes across US 66, heading northeast, passes Gish siding (MP 59.6,capacity 71 cars) in a deep cut heading due east, climbs up past the site of Dell (MP 58.6, closed 1948) into the broad bowl shared with the north tracks (further up the hillside to the north), then edges northeast to come alongside track 1 (but at a lower level) by MP 57.2, where the dirt road crosses track 2 at grade. Curving south, track 2 comes alongside track 1 and reaches the same grade as that track before both tracks turn east together to reach Summit.
At Summit, after the curves, there is a flat and level area, which includes sidings (capacity for 126 cars eastward and 122 westward), crossovers permitting movement among all four tracks, a depot and houses on the north side of the tracks (as well as a former LA Railway Funeral Car named ‘Descanso” located behind and above the houses), with an east-facing spur behind the houses. (Summit Truck Trail crosses the lines at grade just east of the houses. The sidings continue east to just east of MP 55.0. East of the Summit, the line starts to descend towards Barstow. The grade between Summit and Frost is 1.5-1.6%, descending towards Frost.
There is a road crossing at MP 52.8. At Lugo (MP 50.3), there is a westward 98 car siding, where the line is on the hillside above and to the north of Summit Valley Road, which curves along as the tracks curve back and forth. Following another grade crossing, rail line and road turn northeast and continue into Hesperia, at MP 45.1, where there is a 106 car eastward siding and a 99 car westward siding. The Cushenbury Spur heads off to the east at MP 44.9. A concrete underpass connects two sides of Santa Fe Avenue, the main portion of which is alongside the tracks, now up on an embankment, on the west side. There is a 105 car eastward siding on the west side of the tracks at Thorn (MP 41.1).
In the days when this line was signaled as double-track, current-of-traffic (Rule 251), the line between San Bernardino and Thorn was laid out for left-hand running, so that westbound trains used the easier gradients uphill from San Bernardino. Santa Fe built a “natural crossover” north of Thorn, where the westbound line (the more westerly track on the north side of the bridge) climbed up and over the eastbound line as the tracks curve from northeastward to northward in open country.
The Mojave River Narrows are just north of the natural crossoveras the line turns north-northwest, passes under the through-arch road bridge that also crosses the river, and enters Victorville. The Victorville Depot is on the west side of the tracks (MP 35.7), immediately south of the Sixth Street grade crossing; there are also watering facilities at Victorville. There are crossovers just north of the grade crossing, with two 100 car westward sidings and a 98 car eastward siding north of that crossing, as well as a wye on the west side of the small yard, while Route 66 runs alongside to the west. The Mojave Northern goes off to the east at Leon (MP 35.2), which is also the site of the Southwest Portland Cement plant, on the east side of the main line, established in the 1900s. North of Leon, the tracks cross over the Mojave River (which had been on the east side of the line) on a pair of single track through truss bridges, and turn north-northeast, followed by a spur to the west at Adelanto (MP 34.4). There are 108 car eastward and 90 car westward sidings at Oro Grande (MP 31.5), just south of the cement plant on the east side of the line, established in the 1910s, as well as a grade crossing at 1st street, up on the embankment next to and east of US 66, and the line crosses over Mill Street on a stone arch bridge. At the Oro Grande cement plant itself, the line angles towards the northeast, while US 66 passes underneath another stone arch bridge in the embankment at the north end of the plant. From Oro Grande to Barstow, the line descends at a grade of 0.7%. The highway now moves away from the tracks, further east, as the tracks head across the broad agricultural floodplain of the Mojave River. There are dirt road grade crossings, with nothing but crossbucks for protection, over farm roads at Robinson Ranch Road and the south segment of Brymer Road, as well as at the north segment of Brymer Road and Turner Road, a bridge in the embankment over Harris Lane, a grade crossing at Darghty Road, a bridge over something unidentified and the grade crossing at Vista Road, Helendale, MP 21.9.
There are 108 car eastward and 98 car westward sidings at MP 21.1 (Helendale), which also has watering facilities. The line then runs on the east edge of the floodplain, alongside and at the foot of a hillside, on the east side of the line, and at places in short cuttings, temporarily obscuring it from US 66 further to the east. Northeast of this section, with the line itself now running northeast-southwest, there is a grade crossing at Indian Trail Road, MP 17.3, a dirt road along the west side of the line, and a bridge (concrete arch in the embankment) over Holcombe Ranch Road. There is a bridge over something unidentified just south of Hodge, followed by the 106 car eastward and 120 car westward sidings at Hodge (MP 13.6).
There is a grade crossing at Hinkley Road. At Lenwood there are 104 car eastward and 92 car westward sidings and the Lenwood Road grade crossing. The connection between the First District, from San Bernardino, and the Mojave District of the Valley Division, coming almost due east from Mojave is a wye just east of Barstow (MP 0.0). The tail of that wye is at Waterman Spur on the Mojave District. The west end of the yard and depot at Barstow are controlled by West Tower.