Maryland Route 3 (MD 3), part of the Robert Crain Highway, is the designation given to the former alignment of U.S. Route 301 (US 301) from Bowie, Maryland, United States, to Baltimore. It is named for Robert Crain of Baltimore. It is unique in Maryland in that it has a business route and a truck route which do not connect to their parent; however, the business route is also a part of the Robert Crain Highway. MD 3's current orientation is vestigial from the construction of Maryland's freeway system.