Maryland Route 100 - History

History

Maryland Route 100 began in the 1970s as two separate roads, both having the MD 100 designation. The first was known as the Mountain Road Extension, stretching between Governor Ritchie Highway and the old Maryland Route 3, now Interstate 97. The second was built as a short spur between the newly constructed Interstate 95 and US 1 in Elkridge, Maryland. The eastern section, originally known as the Mountain Road Bypass, was constructed east of Ritchie Highway in the late 1970s. MD 100 was completed west of I-97 to I-95, thereby connecting the two roads, in 1994, but it was not completed in its entirety to US 29 until November 1998. A portion of the route between Exit 1B-C and Exit 2 was constructed earlier than the rest as an at-grade boulevard, on the right-of-way of the future eastbound lanes; this section was eventually upgraded.

The construction of the route near Lake Waterford Road severed the original road between Baltimore and Annapolis: the Baltimore-Annapolis Boulevard, signed in part as MD 648. The physical road ends at a pair of dead ends on either side of the right-of-way; MD 648 follows Lake Waterford Road between Baltimore-Annapolis Boulevard and MD 177 before rejoining its original path.

The route is part of the Baltimore Outer Beltway, a 3/4 circular beltway designed to provide a route parallel to the Baltimore Beltway. MD 100 represents the major portion that was built; US 29 between MD 100's terminus and US 29's own northern terminus at Maryland Route 99, four miles (6 km) in length, is another portion. The Outer Beltway was projected beyond MD 99 to run through Howard and Baltimore Counties and intersect MD 140, Interstate 83, US 1, and Interstate 95 before terminating at US 40 northeast of Baltimore.