The two remaining portions of the MD 24 corridor to be built were completed through Edgewood and north of Bel Air in the 1930s. In 1930, Edgewood Road was built as a concrete road from US 40 just west of Van Bibber south to its entrance to Aberdeen Proving Ground at its Pennsylvania Railroad crossing (now Amtrak). Edgewood Road, which was originally designated MD 408, was constructed with a width of but was proposed for widening to as early as 1934 since it was the main entrance to the Edgewood Arsenal. MD 408 received an underpass of the Baltimore & Ohio Railroad (now CSX) and approaches to the grade separation in 1939.