 The first edition of MD 303 was assumed by MD 309 in 1955 when the latter highway was extended north from its terminus in Queen Anne to US 213.MD 303 was assigned to the old alignment of MD 309 between Cordova and Queen Anne in 1961 following the construction of MD 309's present alignment between Cordova and Queen Anne that parallels the railroad grade.The section of MD 303 between MD 309 and MD 404 became one-way northbound in 2004.