The route is divided into the following BNSF subdivisions:
Seattle subdivision from (Vancouver, WA and) Auburn to Seattle
(mileposts from Seattle)
There is a Sounder station at Auburn (MP 21.5x), where there are crossovers, two road bridges overhead, a grade crossing, an oil tank farm on the west side, and the ex-NP line over Stampede Pass comes in from the east on the east-to-north leg of a wye at Auburn North (MP 21.0x), where there are more crossovers.
The line is Double Track, Track Warrant Control (TWC), ABS, and continues north, with a street alongside to the west, past Christopher, a road bridge overhead, two grade crossings, a signal bridge for Intermediate Signals at Thomas (MP 18.5x, track 1 only), a road bridge overhead, a through truss bridge over a river, a bridge over a road, a grade crossing, a trestle at MP 17.09, "Willis", three grade crossings, crossovers and a Sounder station with two side platforms at Kent (MP 16.3x), where the speed limit is 40 mph before reverting to 79-50 to the north, a grade crossing, a signal bridge (Intermediate Signals), a road bridge overhead, the Kent Industrial Lead on the west side (MP 14.1x), a grade crossing, a spur on the west side, a grade crossing, a signal bridge (Intermediate Signals), O' Briens, a street alongside to the east, a road bridge overhead, crossovers at Grillia (MP 12.2x), a line on the west side, a bridge over a road, MP 12x, Glacier Park (MP11.2x), an erstwhile wye with a former NP line east to Renton, and an Amtrak-Sounder station with two side platforms at Tukwila (MP 10.8x).
The speed limit falls to 55-45, and the line expands to Three Main Tracks (of which tracks 1 and 2 are ABS, OCS and track 3 is CTC), at Tukwila, where there are crossovers, dual road bridges overhead, and the UP (ex-Milwaukee) line which has been running along the west side of the BNSF line crosses over to the east side to its Black River location and both lines turn north-northwest. At Renton Junction (MP 9.5x, track 3 only) there is a south-to-east leg of a wye with the former Milwaukee line headed east, now owned and operated by BNSF as far as Renton, to replace that former NP line to Renton, which ran just further south. The north leg of that wye trails in from the southeast at BNSF's Black River (MP 9.1x), where there is a bridge over Black River, crossovers and signal bridges, and a yard entrance on the west side of the line, and the speed limit rises to 75-50.
From Black River northward to South Seattle, there are two extra tracks on the west side and two more further away, and then BNSF's 8-track (or so) South Seattle Yard is on the west side of the tracks, with dual highway bridges overhead, and a road bridge overhead. At South Seattle (MP 7.9x), the north end of the yard, there are two extra tracks on the west side, followed by crossovers. The line passes Rhodes (MP 6.9x), a 9,157 ft. siding off track 3 at Van Asselt (MP 6.4x), where there are crossovers, a detectors at MP 5.2x, Boeing Field on the west side, a signal bridge for the flat crossing with the (three tracks) connectors from the UP line on the east side to its twelve-track Argo yard on the west side at Argo (MP 3.3x), where there are crossovers, the line reduces to Two Main Tracks, CTC, and the speed limit falls to 40-30, with eight tracks in a BNSF yard on the west side.
At Coach Wye (MP 2.5x), the BNSF line into the Seattle Harbor continues ahead, with a very tight wye connection to the main line, while the now Three Main Tracks, CTC, main line turns north, with the Amtrak Coach Yard on its east side past four road bridges overhead, the last for the eponymous Spokane Street (MP 2.1x), where CTC ends and the line continues as DT OCS, past a spur trailing in on the west side, an adjacent road bridge overhead and grade crossing on its north side, a signal bridge overhead, a grade crossing, a five-track intermodal freight depot on the west side, a grade crossing (Lander Street), three extra tracks on the west side for locomotive storage, a grade crossing, six tracks for Sounder train storage on the west side, Safeco Field, the Seattle baseball stadium, on the west side, a grade crossing, Qwest Field, the Seattle football stadium, on the west side, and the passenger station at Seattle (King Street) (MP 0.0x), where the speed limit is 20 mph.
The latter has an island platform, a main platform, serving three through tracks, with two through freight tracks on the east side, on the west side, where the brick-built multi-storey depot with its signature clock tower is located, and two south-facing stub-end platforms, serving four terminal tracks in total, on the south side of the depot. A large pedestrian bridge over the tracks, connecting with the road above the retaining wall on the east side of the line, was built in 2004 for the onset of the new Sounder commuter train service.