This route covers the following subdivisions:
The State Street Line runs from downtown Los Angeles east to El Monte, using tracks formerly owned by Pacific Electric. It starts at State Street Junction (MP 482.4), aka Pasadena Junction on the UP Los Angels sub. along the Los Angeles River, adjacent to the southwest corner of Southern Pacific's Los Angeles Transportation center, just east of downtown Los Angeles, single track, Centralized Traffic Control (CTC), maximum speed 25 mph at the junction, rising to 40 mph thereafter. The line, initially heading south at the junction, turns away to the east, passes under Mission Road, and emerges, two tracks wide, alongside and to the north of Interstate-10, the San Bernardino Freeway. The right-of-way here was once the main eastern route of the Pacific Electric interurban line, four tracks wide, that emerged from the center of Los Angeles and crossed to river along the route now occupied by the freeway. The PE lines to the east of the river at this point closed when the route was condemned by eminent domain proceedings, for the purpose of building the (then) Ramona Freeway in 1951.
Just across the river from the gleaming high-rise buildings of downtown Los Angeles, the area between the river and the Golden State Freeway (Interstate-5) comprises many ramshackle rundown buildings, signed completely in Spanish, reminiscent of the poorer areas of Tijuana, across the Mexican border to the south. The railroad parallels I-10 as it passes under I-5 heading east and climbing steadily, and comes alongside the hill on which Los Angeles County-USC General Hospital is located. As it passes under the intersection of Marengo Street and Soto Street on the southeast edge of the hill, the right of way of the former PE line to Pasadena and the west San Gabriel Valley curves away to the northeast at State Street (MP 486.0). Still clearly visible, this r-o-w was once home to a parade of interurban trains bringing the residents of Pasadena, Sierra Madre, Arcadia and San Gabriel downtown, and visitors to Santa Anita Racetrack and the Pasadena Tournament of Roses in the opposite direction. Today's State Street Line continues along the former right-of-way of the PE line that went all the way to San Bernardino along the Ramona Boulevard corridor.
Passing under a bridge carrying Charlotte Street, the line comes alongside one of the city's municipal housing projects. A pedestrian bridge crosses the line and freeway, and then a road bridge carrying Herbert Avenue. Heading east-northeast, now, the line passes signals at Lincoln Park (MP 487.7), and under Eastern Avenue and then Campus Drive. At this point, the busway built along the San Bernardino Freeway has come alongside to the south, the line and the busway negotiate the bridges carrying I-710 (the Long Beach Freeway) and a plethora of interchange ramps, and cross over the westbound lanes on a bridge to enter the median of the San Bernardino freeway, at this point heading northeast but soon to curve to the east.
In the center of the freeway, the single-track railroad line passes over the many streets and occasional stream crossed by the freeway, but there are no separate bridges for the railroad at any of these locations with the roads and streams being unnoticeable from the perspective of the railroad. The occasional footbridge and road bridge crossing overhead similarly have no independent existence from the railroad's perspective. There are several sets of signals located along the railroad on this segment, at Monterey Park (MP 489.0), where the passenger speed has risen to 50 mph, somewhat east of the Almansor Avenue overbridge, and one set at San Gabriel Boulevard (MP 492.8), between that bridge and the San Gabriel Boulevard busway entrance ramps to its east, where the passenger speed has risen to 60 mph. The freeway, busway and railroad complex passes through a largely residential section of the west Sam Gabriel Valley, with the housing areas in Alhambra, San Gabriel and Rosemead variously populated, in 2004, by a mix of Hispanic and Asian ethnic groups, in housing stock dating largely from (approximately) the 1950s and 1960s. The line here approximately follows the route of the old PE San Bernardino line, which ran along the old Ramona Boulevard in the area now occupied by the freeway. There are more signals at San Gabriel (MP 493.2) and Rosemead (MP 494.8)
At the eastern edge of Rosemead, where the freeway angles south-southeast for a short distance, the railroad exits the freeway median via a tunnel under the westbound lanes, emerging onto a viaduct that crosses the Rio Hondo, past signals at South El Monte (MP 496.2), where the maximum speed has dropped to 30 mph, to enter El Monte, turns north northeast on its east bank (past the El Monte bus station that is the destination of the busway), crosses over Valley Boulevard, turns to the southeast while crossing over Santa Anita Avenue, and descends alongside and to the south of the Southern Pacific "Sunset Route" line, trailing into the south side of that line at El Monte (MP 496.5), where the erstwhile PE line continued directly east, across the SP.