AMP: 0 Location: S-278 and I-15, Beaverhead Cty Reassurance shield at the beginning of S-278, which I would hazard as one of the most, if not the most, important secondary highways in the state. AMP: 43 Location: S-278 and Founier St, Jackson, Beaverhead Cty Not much in the way of signage though. 43 miles later, … Continue reading Montana Secondary Highway 278, I-15/S-222 to MT-43