Maryland Route 100 forms much of what was intended as an outer beltway for Baltimore, and runs between Jacobsville in northeastern Anne Arundel County and U.S. Route 29 between Ellicott City and north Columbia in Howard County, passing south of Glen Burnie and the BWI airport in the process. It has interchanges with interstates 95 and 97, the Baltimore-Washington Parkway, and has an exit serving the Arundel Mills Mall.