Marias Pass, Rail mountain pass in Montana, United States.

Marias Pass is a mountain pass at 5,213 feet (1,589 m) in the Lewis Range, on the southern border of Glacier National Park. It carries US Highway 2 and the BNSF Hi-Line Subdivision across the Continental Divide, between the Lewis and Clark and Flathead national forests. Its broad, open valley, one to six miles wide, gives a gentle grade.

Marias Pass was long known to Native Americans and fur trappers, but its railroad potential was only recognized in the mid-19th century. In 1853 Isaac Stevens led a Pacific Railroad Surveys party; his engineer Abiel Tinkham missed the pass, and James Doty later followed an old Indian trail up the Marias but did not continue west. In December 1889 John Frank Stevens, with a Flathead guide named Coonsah, finally explored and charted the pass for the Great Northern Railway.

The Blackfeet knew the pass as a broad, open valley and, according to chief Little Dog, once used it as their main route across the mountains before abandoning it for some years out of superstition. In 1889 the Flathead guide Coonsah, who had been staying with the Blackfoot in Browning, led engineer John Frank Stevens to the pass. Amtrak's Empire Builder still carries passengers over the line today.

The area remains accessible year-round, though winter conditions can bring snow and variable road situations. Travelers should prepare for changing weather and check current conditions before making the crossing.

The pass was charted only in December 1889, when Great Northern engineer John Frank Stevens found it with Coonsah, a Flathead guide who had been staying with the Blackfoot in Browning. Its broad, open valley, one to six miles wide, needed little excavation or rockwork for the railway.