AMP: 31 Location: US 89 and Going to the Sun Rd, St Mary, Glacier Cty About 7 miles later, we’ll enter unincorporated St Mary. AMP: 31 Location: US 89 and Going to the Sun Rd, St Mary, Glacier Cty In St Mary, turn right for the Going to the Sun Rd through Glacier, which is … Continue reading U.S. Route 89, S-464 to MT-49