From the various connections at BNSF Connection (MP 2.5), known on the BNSF as UP Connection and once known as Napa Street Junctions, with the former Northern Pacific main line headed almost east-west, the former GN Kettle Falls line trailing in from the northwest, a line southeast to UP's Spokane yard, and the start of the UP-owned Spokane International headed east-northeast, the latter line, single track, Yard Limits, speed limit 10 mph, passes the 2,190 ft. siding at SI Yard (MP 2.7), where Yard Limits end and Track Warrant Control (TWC) starts, a branch from West Spokane once trailed in on the north side, and there is a yard on the north side.
The line turns just north of east past Parkwater, Millwood-Irvin (MP 6.8), where a branch once continued straight ahead and the line turns south-southeast, passing underneath the former NP line, and turning southeast and then east, bridging over the Spokane River and turning east-northeast, past Trentwood-Velox (MP 10.8), where a large Kaiser Aluminum plant fills the area between the UP and the BN line to the north, a spur at Austin (MP 12.7), after which the speed limit rises to 40 mph, Otis, Lucky Spur, East Farms (MP 17.7), passing from Washington into Idaho, past a spur at Interstate (MP 20.2), the 2,690 ft. siding at Grand Junction (MP 21.7), and the flat crossing at BNSF Crossing (MP 22.0), where there is a flat crossing (20 mph on the crossing) with a former NP branch and was once a flat crossing with the erstwhile Milwaukee Road line north to Newport.
The line’s direction gradually turns from east to northeast, through the 1,730 ft. siding at Coeur D'Alene Junction (MP 25.3), where the speed limit is back to 40 mph and the branch southeast to Coeur d’Alene leaves, Haycroft (MP 26.6), a detector at MP 28.9, Garwood, where it turns north-northeast, Chilco (MP 36.2), Corbin Junction, where a branch to Bayview once continued ahead and the lien turns north, passing under the BN before reaching Athol (MP 42.7), then turning away from the BN to the north-northwest, west, and north again, past the 7,270 ft. siding at Clagstone (MP 50.1), where a Milwaukee Road branch once left to the west, a detector at MP 51.8, Edgemere, the 8,615 ft. siding at Vay (MP 57.6), Sawyer, Colalla, Morton and Gravel, curving east across the Pend Oreille River into Dover (MP 71.5), where there is a connection to the rump of the BNSF (ex-GN) Newport subdivision, which the UP uses north to North Sandpoint and Boyer (having abandoned a segment of its own line through Sandpoint), and the Pend Oreille Valley shortline (formerly the GN main line) west, along the eponymous river valley, to Metaline Falls.
The UP returns to its own line with a connection east from North Sandpoint to its former Sandpoint location, turning north to the flat crossing with the BNSF Kootenai River subdivision (ex-GN) at BNSF crossing (MP 75.3), where the speed limit is 10 mph on the crossing and the 7,716 ft. siding at Sandpoint (MP 76.0), where the speed limit is back to 40 mph, and continuing north, parallel to the BNSF (ex-GN) main line, but to its east, past a detector at MP 81.3, Forest Siding (MP 82.1), the 2,205 ft. siding at Samuels (MP 86.8), where the ex-GN draws near on the west side, Elmira (MP 90.2), and McArthur, turning northeast and then north again, alongside the ex-GN, past the 4,435 ft. siding at Shiloh (MP 95.8), where the speed limit is 35 mph, Naples, where the line becomes curvy and moves away from the GN to the east (but still heading north), a detector at MP 97.7, where the speed limit is 30 mph, and Brown Creek where it straightens out due north, passing above the ex-GN as it jogs to the east in a tunnel.
The UP then runs roughly parallel to the BN's on the latter's west side, but above it on a wooded hillside, past a spur at Deep Creek (MP 103.7), where the speed limit is back to 40 mph, and Burns, where the ex-GN turns away northeast, turning east past Schooner, the 6,432 ft. siding at Bonners Ferry (MP 109.0), and the flat crossing with the BNSF Kettle Valley line at KV crossing (MP 109.3), where the speed limit falls to 25 mph, turning northeast and bridging over the Kootenai River, and turning curvily east, on a ledge on the hillside north of the Kootenai River, past Saddler Siding and a detector at MP 111.0, and then turning northeast past a detector at MP 114.6 and 382 ft. Tunnel 1 (MP 114.6), east past 372 ft. Tunnel 2 (MP 115.1), and south and then east again past 322 ft. Tunnel 4 (MP 117.0), on the hillside just above the river, with the ex-GN running along the far bank of the river, below.
The line finally turns away from the BN (ex-GN) line to Montana some miles east of Bonner’s Ferry, turning north, northeast past the 1,730 ft. siding at Moyie Springs (MP 119.1) and curvily north past the spur at Mesenbrink (MP 119.8), Eileen, a detector at MP 123.2, a detector at MP 126.5, where the speed limit has risen to 30 mph and the line is curving back and forth, a spur at Meadow Creek (MP 126.7), Snyders, where the line has generally straightened out heading north, Sinclair Spur and Addie to the 3,990 ft. siding at Eastport (MP 140.7), where the speed limit has risen to 40 mph and the line makes an end-on junction with the Canadian Pacific at the US-Canadian Border (with Kingsport, BC).