The Trolley Line #9 Trail is a 1.25-mile (2.0 km) trail in western Baltimore County, Maryland. It begins at the west end of Edmondson Avenue and extends from Catonsville through Oella to Main Street, Ellicott City. The trail follows what was originally part of the Catonsville and Ellicott City Electric Railway Company trolley line that shuttled passengers between Ellicott City and Baltimore from the late 1890s to the mid-1950s.