AMP: 16 Location: SH-77 Spur and SH-77, Cassia Cty SH-77 Spur isn’t really signed with its numerical designation, but it is well signed as the California Trail and City of Rocks Backcountry Byway. I’m not sure why this newer highway to the system (appeared in the mid-2010s) didn’t just get its own number. AMP: 16 Location: SH-77 … Continue reading Idaho State Highway 77 Spur, SH-77 to City of Rocks Nat’l Reserve