The Feather River Route is divided into the following subdivisions:
Canyon Subdivision from [Oroville and] Keddie to Portola
Winnemucca Subdivision from Portola to Winnemucca
Elko subdivision from Winnemucca to Weso [and Elko]
The west leg of the wye starts at Keddie Wye (MP 280.5), curving south across the southerly trestle, with the east leg through the tunnel from the "High Line" trailing in from the northeast at Keddie (MP 280.7, whence there is a 7,386 ft. siding south-southwest and then around the curve to the southeast to MP 282.3, with the depot and other buildings on the west side of the tracks. The line continues east, with speed limit still 25 mph, single-track, CTC, along the north side of Spanish Creek, turning southeast through 1,266 ft. Tunnel 33 (MP 283.1) and east through 305 ft. Tunnel 34 (MP 283.7) past the former location of a detector at MP 284.0, before turning south-southeast to Spanish Creek, then east-southeast, turning southwest, bridging over Spanish Creek again in the process, and then leaving the valley of the Middle Fork of the Feather River behind, as it passes a detector at MP 285.3 and then curves gently around to the southeast to reach Quincy Junction (MP 288.2), the junction with the Quincy Railroad, a shortline serving the town of Quincy.
East of the junction, the line continues southeast, turns east to the former location of a detector at MP 290.0, and then south past Massack (MP 293.6), and south-southeast past the former location of a detector at MP 293.8. Part of the altitude gain needed to accomplish the crossing of the divide between the Middle Fork of the Feather River and the South Fork of that river (while maintaining the maximum grade goals of the promoters of the line) is accomplished by means of Williams’ Loop (MP 294.3), a counter-clockwise circle more than a mile in circumference. Because this loop is so large, and runs through a forest rather than open countryside, it is impossible to view it all at once, in the way that Tehachapi Loop can be viewed. In part for this reason, Williams’ Loop is much less known than its southerly counterpart.
The line exits the loop heading southeast past the 4,610 ft. siding at Spring Garden (MP 295.9-296.8), where the line runs along the north side and at the same height as a bubbly stream, several yards in width. The line then turns south through 7,336 ft. Tunnel 35 (MP 297.2), passes a detector at MP 300.0, and then turns east, running alongside the South Fork of the Feather River, on its north side. Even though the line is now in another river valley, it is still climbing towards its eventual summit. The line passes the 7,869 ft. siding at Sloat (MP 301.1-302.7), where the speed limit rises to 30 mph, curving south-southeast, following the river, past Cromberg, a detector at MP 305.2, Two Rivers (MP 305.4), where the line turns south, and then southeast past the former location of a detector at MP 308.0, and Feather River Inn to the 4,869 ft. siding at Blairsden (MP 309.9-311.0).
The line then turns south-southeast, past the former location of a detector at MP 312.6, east through Clio, northeast and east again, across Clio Trestle, above the river as it crosses from one side of the valley to the other, past the former location of a detector at MP 314.7, turning north through 763 ft. Tunnel 36 (MP 316.0), crosses the river again, past the former location of a detector at MP 316.7, turns northeast past Mabie (MP 318.3), crosses the river again past the former location of a detector at MP 319.2, after which the line reaches the yard and crew change point at Portola, where there is also a 10,748 ft. siding (MP 320.2-322.3), with the Portola Railroad Museum along the southeast side of the line.
At the east end of Portola, the line turns due east with speed limit now 70 mph, past Calpine Junction, where a WP branch once headed south to Calpine, across the river again, past the 5,857 ft. siding at Hawley (MP 326.9-328.1), whence a branch heads southeast to Loyalton from the west end, past a detector at MP 335.9, across the river for the last time, past the 6,342 ft. siding at Chilcoot (MP 338.5-339.7) to the summit of the line at Beckwourth Pass (elevation 5,018 ft.), marked with the west end of 5,999 ft. Tunnel 37 (MP 340.3). The line then descends slowly into basin and range country, which includes several rivers with no outlet to the sea. At Reno Junction (MP 341.5), where the speed limit is 50 mph and there is a 6,131 ft. siding and a wye with the Reno branch heading south, the main line turns directly north, and then, with speed limit 40 mph, passes the 6,213 ft. siding at Scotts (MP 344.9-346.2), where it curves north-eastward, curving back and forth around the edge of the mountains to the west.
The line passes Pozla (MP 348.9), and then turns north past a hold signal at Red Rock (MP 352.2), curving west-northwest across a river, past Constante, and then north again, across the river again, past a detector at MP 358.3, where the speed limit has risen to 60 mph, across the river again, past the 6,456 ft. siding at Doyle (MP 361.9-363.2), and across the river for the last time, to the 4,279 ft. siding at Herlong (MP 371.2-372.1), where it turns east to head past the Sierra Army Depot, on the north side of the track at East Army (MP 373.1), where there is a line north into the Army Depot, and the speed limit rises to 70 mph, and passes Caheva, into Nevada.
At the 6,258 ft. siding at Flanigan (MP 382.9-384.3), the SP Modoc line trails in from the west-northwest, and the speed limit drops to 60 mph. The main line then turns northeast past a detector at MP 387.1, where it turns north, east, north again, over Sand Pass, where the speed limit is 35 mph and there is a a 6,234 ft. siding (MP 393.1-394.4), turning east again in the process, then curving back and forth and turning north-northeast past Bryant and north past the 6,235 ft. siding at Sano (MP 404.1, where the speed limit is 55 mph, to MP 405.4, where it is 70 mph) and a detector at MP 412.8, edging gently to the north-northeast past the 5,739 ft. siding at Reynard (MP 415.7-416.9) and Bronte, turning southeast at the 6,245 ft. siding at Phil (MP 430.5-431.5), where the speed limit is 60 mph, and a detector at MP 434.5, where the speed limit rises to 70 mph again, and northeast through the 6,380 ft. siding at Gerlach (MP 437.3-438.6), at the north edge of an extensive dry mud flat, onto which a line to Empire once ran southeast from a wye at the west end of Gerlach.
The line continues northeast across the desert, past Ascalon, the 6,220 ft. siding at Trego (MP 450.6-451.6), a detector at MP 456.0, the 6,243 ft. siding at Cholona (MP 460.6-461.9), and turns east past the 6,246 ft. siding at Ronda (MP 469.9-471.2), before turning northeast again at Sulphur (MP 474.5), a detector at MP 475.1, and the 6,163 ft. siding at Floka (MP 478.7-480.0), and east-southeast, with speed limit 60 mph, past the 6,246 ft. siding at Antelope (MP 487.0-488.2), after which it turns just north of east, northeast, and east, then just north of east again. There is a 6,130 ft. siding at Jungo (MP 496.0-497.2), where the speed limit has risen to 70 mph again, a detector at MP 503.9, and the 6,249 ft. siding at Gaskell (MP 507.9-509.2), and the line turns just south of east past Pronto to the 6,223 ft. siding at Raglan (MP 518.5-519.8), where it turns east past a detector at MP 521.4, where the speed limit is briefly 60 mph before resuming 70 mph, Krum, where the line edges just north of east again and then turns east past Marcus (MP 525.8).
The line crosses the Humboldt River and turns northeast past the west end (MP 530.7) of the 10,007 ft. siding on the northwest side of the line at Winnemucca (MP 530.8), where a 7,091 ft. siding on the southeast side of the line starts, with the latter ending at MP 532.1 and the former at MP 532.8. At Weso (MP 535.8), just east of Winnemucca, the paired track with the SP starts, with crossovers between the two lines, and continues through the Humboldt River valley.