The line currently runs from the Lutherville Light Rail Stop to International Circle near Hunt Valley Town Center, serving the Timonium and Cockeysville areas.

[5] Originally, Route 9 operated to/from downtown Baltimore during peak hours, and had a southern terminus at Towson State University at other times.

Selected trips and deviations were added to International Circle, Loveton Business Park, and developing residential, commercial, and industrial areas.

All service south of Northern Parkway was eliminated, except for a few early morning northbound trips before the opening of the light rail, which followed the line's old route.

The southern off-peak weekday terminus was moved to the Lutherville Light Rail Stop to eliminate duplication with Route 8.

[8] In October 2005, as part of the Greater Baltimore Bus Initiative, a comprehensive overhaul plan for the region's transit system, Route 9 line was re-introduced after a 5-year absence.

[9] Initially all trips on route 9 would terminate at Hunt Valley Town Centre but due to weight restrictions Hunt Valley Town Centre management prohibited MTA buses from being allowed to enter the premises in June 2005 before the reinstatement of route 9.