And if you do the NT, you can walk across the Mississippi at Lake Itasca.
Some people balk at Glacier because they think they have to do the part in Candada to get there. Not so. From Cut Bank, MT you can take U.S. 2 to Browning then Starr School Rd. to U.S. 89 north, which will take you to St. Mary and the west entrance to the park.
The section between Cut Bank and Magrath, Alberta (home to a Hutterite community) is long and lonely 71 miles.