Mountain Transit serves the San Bernardino Mountain communities of Crestline, Lake Arrowhead, Running Springs, and Big Bear Lake, providing local service for more than 163,000 passengers each year.

Weekend service on Mountain Transit's Big Bear OTM provides 2 round trips on Saturday and Sunday, and two round trips on Saturday from the RIM OTM (Crestline, Lake Arrowhead, and Valley of Enchantment).

[8] In 2021, local bus routes in the Big Bear valley were made free as a way to reduce congestion within Big Bear[9][10][11] In 2023, bus routes in Crestline and Lake Arrowhead were made free as a way to reduce congestion[12] Mountain Transit is administered by a board of directors made up five members: two from Big Bear Lake, one member at large, and two Supervisors of the County of San Bernardino.

It is required under the JPA that the board of directors meet at least one time each quarter of each fiscal year.

Board meetings are held the third Monday of every month (except January* and February*) at 1:00 p.m. with location alternating between Big Bear Lake and Crestline.