Missoula sits where five mountain valleys meet along the Clark Fork River, and its highways follow those valleys out of town. I-90 runs along the north side of the city, heading west toward Idaho and east toward Butte. US 93 runs north over Evaro Hill toward Flathead Lake and south through the Bitterroot Valley toward Hamilton. US 12 heads southwest from Lolo over Lolo Pass into Idaho, and MT 200 heads east up the Blackfoot River from Bonner. Reserve Street is the main commercial corridor, Brooks Street runs diagonally from downtown toward the south side, and Higgins Avenue crosses the river into downtown.
Reserve Street is the city's busiest road, lined with shopping centers and backed up most afternoons. The bridges over the Clark Fork are choke points, and the I-90 interchanges at Reserve Street and Van Buren slow at rush hour. The mountain grades around town, from Evaro Hill to Lolo Pass to the long climb toward Lookout Pass, are where highway breakdowns tend to happen, especially when brakes or cooling systems are already worn.
Missoula Montana Airport is northwest of the city near I-90. Mountain Line buses run throughout the city and to the university, and many students and commuters ride or bike rather than drive, so cars here often sit for days between trips.
Two seasonal patterns shape driving: winter inversions that trap cold air and fog in the valley for days, and summer wildfire smoke that can settle over the city for weeks. On the worst inversion days, freezing fog coats windshields and wipers with a stubborn glaze.