AMP: 78 Location: US-87 and S-236, Chouteau Cty Reassurance shield as we head out of Big Sandy. AMP: 51 Location: US-87 and 3rd Ave, Loma, Chouteau Cty Several miles later, we’ll enter Letter of Map Amendment. AMP: 43 Location: US-87 and S-387, Chouteau Cty As we near Fort Benton, we’ll come to a junction with S-387. 387, combined … Continue reading U.S. Route 87, S-236/S-432 to S-387