The Mountain Line provides public transportation bus service in the Flagstaff area of Coconino County, Arizona.

It started in 2001, replacing the county-run Pine Country Transit.

[1] There are nine routes currently in service (2, 3, 4, 5, 7, 8, 10, 14 and 66).

Every route currently in service interchanges at the downtown connection center, located on W. Phoenix Ave at S. Mikes Pike and at the Flagstaff Mall connection center located on E. Mall Way and N. Marketplace Dr. at which 3 routes (2, 3, 66) transfer.

Paratransit service in Flagstaff is supplied by Mountain Lift, another operation of NAIPTA.