At Sandpoint Junction (MP 1403.3), the former NP line now owned by Montana Rail Link turns away northeast, a connection to the UP (SI) line continues straight ahead, and the BN-built connector over to the ex-GN line turns away west-northwest, crossing the SI on the flat at UP Crossing (MP 1402.5), and joining the original GN formation at the 10,363 ft. siding at Boyer (MP 1401.3), where a remnant of the original GN line trails in from Metaline Falls along the Pend Oreille River to the west. From this point, the line heads north, with speed limit 79-60 over the single-track, CTC, line.
There is a detector at MP 1398.6, Bronx, a 7,439 ft. siding at Colburn (MP 1394.1), as the line turns east-northeast, a spur on the northwest side to W.I. Forest Products (MP 1393.5) as it turns northeast, Samuels (MP 1391.3) as it returns north-northeast, a 9,9912 ft. siding at Elmira (MP 1387.4), as the former SI approaches on the east side, McArthur as both lines turn east-northeast, a detector at MP 1381.6, where the speed limit is 70-60 and the lines curve north again, and a 9,577 ft. siding at Naples (MP 1379.8), where the ex-SI moves away on the east side. The main line turns northeast to pass under the former SI in 479 ft. Tunnel 10.2 (MP 1376.2), where the speed limit drops to 45-40, curves northwest and then back to the northeast, as it passes through 610 ft. Tunnel 10.1 (MP 1374.1) and passes Moravia (MP 1373.3), then turns east, north and northeast again to Bonnerís Ferry (MP 1368.4), where the speed limit is 50-45 as Two Main Tracks, CTC, begin, and 60-55 thereafter.
The line turns east, entering and then following the Kootenai River valley, on the south side of the river, past crossovers at CP 13663 (MP 1366.3), detectors also at MP 1366.3, curves east-northeast past Crossport (MP 1364.3), east to East Crossport (MP 1363.4), where the 2MT reduce to single track, CTC, and the speed limit drops to 35-30 along the curvy river bank, curves east-southeast, northeast (on a stretch where the line is clearly visible from the ex-SI, partway up the hillside across the river), north, east through 394 ft. Tunnel 10 (MP 1359.9) and 992 ft. Tunnel 9 (MP 1359.5), south past the 10,440 ft. siding at Katka (MP 1357.8), east and then south-southeast past a detector at MP 1356.6 and the 8,235 ft. siding at Leonia (MP 1350.3) into Montana, south, east, southeast through 192 ft. Tunnel 8 (MP 1348.5), south-southeast through 731 ft. Tunnel 7 (MP 1346.9), south and south-southeast again, past the 11,082 ft. siding at Yakt (MP 1343.3), where the speed limit has risen to 45-40, southeast past a detector at MP 1340.9), and south-southeast again past the 14,286 ft. siding at Troy (MP 1337.9), where the speed limit is 60-55.
Tunnel 6 (1,396 ft., MP 1335.3) is on a curve southeast, after which the line turns east past the 8,641 ft. siding at Kootenai Falls (MP 1331.3), where the speed limit is 45-40, curving back and forth along the river bank, and east-southeast at Rankin, where the speed limit rises to 60-55, past a detector at MP 1324.1 to the 10,510 ft. siding at Libby (MP 1319.6), where there is a passenger station. The line turns northeast, curves east past a detector at MP 1315.9, and turns south at Zonolite (MP 1314.8), east-southeast at the 9,568 ft. siding at Ripley (MP 1312.2) and east to Jennings, where the original GN main line turned north to follow the Kootenai River valley to Rexford before turning southeast to Stryker. Today's line instead turns south, away from the river, on the diversion necessitated by the construction of the Libby Dam creating Lake Koocanusa (which runs north into Canada, where the river arises) in the Kootenai River valley.
The diversionary line (actually, at this point, the former GN line via Haskell Pass to Kalispell) passes the 10,799 ft. siding at Riverview (MP 1306.9), and turns just north of east at the 9,769 ft. siding at Fisher River (MP 1298.0), where the speed limit rises to 75-60 and then 79-60, past a detector at MP 1296.1, Sterling, and the 10,344 ft. siding at Tamarack (MP 1290.0) before the diversionary route diverges northeast from the now closed Haskell Pass line, turns north past the 9,730 ft. siding at Wolf Prairie, northeast past a detector at MP 1276.4, and north-northwest past the 9,760 ft. siding at Rock Creek, and then turns north through the 7.0 mile Flathead Tunnel (MP 1264.6), where the speed limit is 50 mph, emerging past the ventilation plant to the 9,763 ft. siding at Twin Meadows (MP 1263.5).
The speed limit rises to 79-60, the line turns east-northeast at Swamp Creek (MP 1260.4), north-northeast past a detector at MP 1258.1), and northeast past the 9,722 ft. siding at Brimstone (MP 1252.8), before turning southeast, up on the southwestern hillside above the original alignment (near Trego on the still extant segment from Eureka), descending and rejoining the original alignment trailing in from the north-northwest at Stryker (MP 1249.3), where the speed limit is 70-60 through the junction, before retuning to 79-60 past the 9,711 ft. siding at Radnor (MP 1243.3) and then dropping to 65-60 past a detector at Olney (MP 1236.6) and the 9,325 ft. siding at Lupfer (MP 1231.1), turning south and then east-northeast through 0.2 mile Tunnel 5A (MP 1226.8), east and then curvily south along the west shore of Whitefish Lake, where the speed limit is 55-50, past Vista (MP 1224.6), and then east at the south end of the lake to the division point at Whitefish, where there is a yard and helper terminal and the half-timbered depot is on the south side of the tracks.
East of Whitefish, where the speed limit is 20 mph and there are Two Main Tracks, CTC, the line turns east-southeast, the speed limit rises to 70-60, and the line passes detectors at MP 1212.9, and crossovers at Halfmoon (MP 1212.8), where the speed limit is 70-45, a 4,015 ft. siding on the south side, and crossovers, at Columbia Falls (MP 1211.6), where there is a wye junction on the south side at which the line northeast from Kalispell trails in. The line then heads generally eastward, now single-track, CTC, with speed limit 40-35along the Flathead River valley (on the north side of the river, with the highway on the south side), starting its climb over the Rockies, past Conkelley (MP 1208.7), a detector at MP 1208.3, and Tunnel 5 (MP 1207.6), turning north and crossing the river past the 11,157 ft. siding at Coram (MP 1203.9), where the speed limit has risen to 60-50, east and then north past Lake Five, east past Grizzly, north past a detector at MP 1198.9, and then east again.
From the 10,232 ft. siding at Belton (MP 1196.1), aka West Glacier, located adjacent to the west entrance to Glacier NP, where the depot is on the south side of the tracks, the line, running curvily east along the south bank of the river with speed limit 50-45, passes Tunnel 4 (MP 1194.5), Tunnel 3.9 (MP 1194.0), Silvertip, Tunnel 3.8 (MP 1192.5), a detector at MP 1192.2, and Tunnel 3.7 (MP 1191.2), turns south-southeast and climbs through Sheldon and Nyack (MP 1188.0), east-southeast past Red Eagle (MP 1185.2), where Two Main Tracks start and the speed limit rises to 60-45 and detectors at MP 1185.1, south-southeast past Hidden lake, Sink Hole, Paola (MP 1177.6), where single track resumes and the speed limit falls to 50-40, Tunnel 3 (MP 1176.7), and Tunnel 2 (MP 1176.2), and turns south past a detector at MP 1175.1, and Pinnacle (MP 1173.2), where the speed limit falls to 45-40 and Two Main Tracks start again, the spur at Essex Pit (MP 1183.1), and detectors at MP 1170.3, to reach the helper terminal (with its wye) and crossovers at Essex (MP 1170.2), where the Izaak Walton Inn is located at trackside (on the east side, as are the helper facilities), and the station (no depot) at which Amtrak serves Essex, on a southeasterly segment just "east" of the helper terminal and Inn.
The line continues southward along the south (west) side of the middle fork of the Flathead River, in the ever narrowing valley between sheer rock mountains (located in Glacier National Park on the east/north side of the line), through Snowshed 12, turning southeast across Sheep Creek Trestle (with the famous Goat (Salt) Lick just downstream, south past detectors at Java West (MP 1166.1), where the speed limit drops to 30-25 and the line reduces to single track, southeast across Java Creek Trestle over the Flathead River to Java East (MP 1165.2), where 2MT begin again and the line turns east-northeastward along the north side of a deep canyon, through Snowshed 11, detectors at MP 1162.1, northeast past Snowshed 10, Singleshot, Snowsheds 9 and 8, north past Snowshed 7, northeast past Snowsheds 6 and 5, east, northeast, north, and northeast again to Blacktail (MP 1157.6), and then northwest up a side valley, around a clockwise horseshoe, southeast to the main valley, northeast past McCarthyville, across another side stream, and then east across a somewhat wide valley, northeast, north and east to the crossovers at Marias (MP 1152.2), then north and northeast to the Continental Divide (el. 5,213 ft.) at Summit (MP 1149.4), where the speed limit rises to 40-35 as the 2MT reduce to single track again.
The line now descends, with speed limit 50-45, past Pike, False Summit, a detector at MP 1145.5, the 9,536 ft. siding at Bison (MP 1144.0), Cataract, a detector at MP 1142.5, and Rising Wolf, turns east-northeast to Talbot, and north past a detector at MP 1138.8 to reach the seasonal station at (East) Glacier Park. The depot is on the north side of the track. The massive Lodge, built by the Great Northern railway to promote tourism, is adjacent to the station. East of Glacier, the climb over Marias Pass is concluded and the high plains begin. Turning northeast, with speed limit 45-40, and passing over the Two-Medicine Bridge, a large trestle, the line then turns east past Grizzly (MP 1136.1), where 2MT begin again, the line curves back and forth on the high plains, northeast with speed limit 65-50 to Spotted Robe (MP 1131.8), where single track resumes, north and then east-northeast past Triple Divide and Dirham, then east, south, and east again
At the 12,183 ft. siding at Browning (MP 1123.9), where the speed limit is 55-50, the east face of the Rocky Mountains in Glacier National Park can be seen in all its glory, and there is a run-down depot, at the location seasonally (Winter) used by Amtrak, on the north side of the tracks. The speed limit rises to 70-60 as the line turns northeast past Kipp and a detector at MP 119.1, east-northeast past Blackfoot (MP 1116.2), where the speed limit rises to 79-60 and 2MT begin again, northeast, east, and east-northeast past a spur at Meriwether (MP 1110.3) and the crossovers at Piegan (MP 1106.5), and east past a spur at Pardue Simmons (MP 1100.5), Sundance, detectors at MP 1099.0, Opel, Gunsight and Garnet before turning southeast to Cut Bank (MP 1090.1), where the speed limit is 30 mph and there is a depot on the south side of the tracks, five grain elevators on the south side of the tracks and one on the north side, all rail-served, and crossovers on the east side of town, where the 2MT end and the speed limit rises to 79-60.
The line turns east past a Union Oil spur at MP 1085.1, southeast past Boru, east at Ethridge, where 2MT begin again, past detectors at MP 1077.8, a jog southeast, Simla, crossovers at Teton (MP 1068.4), where the speed limit drops to 65-45 and a single-track line south from Calgary trails in from the northwest, a massive signal bridge controls the crossovers between the line that trails in, the two tracks from the west. and four tracks to the east (into the yards on both sides of the tracks and the station area), and the line turns southeast. The yards are west of the small wooden depot at Shelby (MP 1065.4) on the north side of the tracks.