Maryland Route 100 (MD 100) is a major east–west highway connecting U.S. Route 29 (US 29) in Ellicott City (just north of Columbia) and MD 177 (Mountain Road) in Pasadena. MD 100 also connects to Interstate 95 (I-95), US 1, the Baltimore–Washington Parkway (MD 295), and I-97. The highway connects Howard County to the west with Anne Arundel County and the Chesapeake Bay to the east. MD 100 also provides access to the Baltimore–Washington International Airport (BWI) and the Arundel Mills shopping mall. The eastern section of MD 100 in Anne Arundel County is known as the Paul T. Pitcher Memorial Highway. The name comes in dedication to Paul T. Pitcher, an Anne Arundel County executive, who originally conceived the highway.

Route description

The route begins as a six-lane divided freeway at US 29 near Ellicott City. There are then interchanges with MD 108, MD 104, Snowden River Parkway and MD 103. At the junction with I-95, the road narrows to four lanes. Then MD 100 intersects with US 1 followed by an exit for the Dorsey station along MARC's Camden Line. It then crosses the Baltimore-Washington Parkway. MD 100 then intersects with MD 170 (Telegraph Road) where the road becomes 6 lanes. Then the road junctions with Interstate 97 near Hanover and reduces down to 4 lanes before crossing MD 2. Between Glen Burnie and Jacobsville, MD 100 serves as a bypass for MD 177, and has interchanges with MD 10 and MD 607. The road ends by merging back into MD 177.

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. 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 was to be part of the Baltimore Outer Beltway, a proposed freeway that would have encircled parts of the Greater Baltimore area and 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.

<!-- History notes The first portion of MD 100 was constructed as a westward freeway extension of MD 177. This highway was under construction from MD 3 (now I-97) east to MD 2 by 1963. The MD 177 freeway opened in 1964 with intermediate interchanges at MD 174 and Oakwood Road. In 1966, the freeway was extended slightly east to terminate at the non-freeway portion of MD 177 at an intersection at the site of today's ramps to and from westbound MD 100. By 1967, an extension of the freeway east to beyond Jacobsville was proposed. This eastward freeway extension opened in November 1970. By 1971, that extension and the portion of the highway between MD 3 and MD 2 were designated MD 100. The portion of MD 100 east of MD 2 originally included one interchange, at Catherine Avenue, and the present three at-grade intersection with a southern extension of MD 607, Magothy Beach Road, and MD 177. The partial interchange with Edwin Raynor Boulevard, then named Tick Neck Road, was added in 1987. That same year, the ramp from southbound MD 2 to westbound MD 100 was added. The partial interchanges with MD 10 opened when the Arundel Expressway opened north to MD 648 in October 1988 and south to MD 2 in March 1991. A disjoint section of MD 100 was constructed in 1970 from I-95 to US 1 near Elkridge. This segment, which was four lanes except for a two-lane section at the US 1 intersection, opened in July 1971 contemporaneously with the portion of I-95 between I-495 and I-695. This part of MD 100 would remain separated from the rest of MD 100 for 25 years. Milestones: p. 8: July 1971 - Opening of I-95 from the Baltimore Beltway to the Capital Beltway in Baltimore County, Howard County, and Prince George’s County. This roadway was originally scheduled to be opened in November 1970, but construction delays in the vicinity of the Baltimore Beltway delayed the planned opening. p. 13: November 1998 - Opening of MD 100 in Anne Arundel County and Howard County. This roadway was opened in the following sections. November 1970 from MD 177 / Mountain Road in Sharonville to MD 2 / Governor Ritchie Highway. September 1994 from US 29 to MD 104. November 1996 from I-95 to MD 295, and from MD 295 to I-97. November 1998 from MD 104 to I-95. Maps: 1963: Divided highway under construction from MD 3 to MD 177 just east of MD 2; interchange boxes at MD 174, MD 3 Bus, and MD 2 1964: Highway complete along 1963 route with 1963 interchanges; marked as MD 177 1965: marked as freeway, interchange at Oakwood Road instead of MD 3 Bus 1966: I-95 proposed with interchange box north of MD 103 1967: MD 100 proposed from MD 2 to east of Jacobsville; proposed to have a standard junction with MD 10 1969: highway proposed for 1 mi on either side of I-95, does not reach to US 1 1970: MD 100 proposed to have the current staggered junction with MD 10; highway proposed or under construction from I-95 to US 1; two lanes near eastern end 1971: MD 100 complete; MD 177 renumbered MD 100 west of MD 2; interchange at Catherine Avenue; old connection to old MD 177 still present; I-95 open; connector between I-95 and US 1 marked as MD 100 1987: Edwin Raynor Blvd ramps added (then Tick Neck Road); ramp from SB MD 2 to WB MD 100 added 1989: MD 10 north interchange built 1991: MD 10 south interchange built 1993: MD 176 upgraded to divided highway on either side of MD 295 interchange, which is rebuilt as a cloverleaf; MD 100 proposed from I-97 to US 1, with gap at MD 176; MD 100 proposed from MD 104 to US 29; US 29 upgraded to freeway, including construction of MD 103 3/4 diamond. Ramp from NB US 29 to EB MD 100 built, ends at loop at Long Gate Parkway 1995: MD 100 built from I-97 to I-95, with modern interchanges; no interchanges at Dorsey MARC or Coca Cola Blvd; full US 29 interchange complete and remaining Long Gate Parkway ramps completed as well as divided highway bridge; undivided highway (two or four lanes?) from Long Gate Parkway to MD 104, marked as MD 100 1997: Coca Cola Drive and Dorsey MARC interchanges built; divided highway extended short distance south from Long Gate Parkway; under construction from MD 104 to I-95, as is Snowden River Parkway extension from MD 108 1999: MD 100 complete Bridges: MD 100 flyover ramp over EB MD 100 at MD 2: 1963 MD 2 (both): 1963 MD 174 (both): 1963 MD 3 Bus (both): 1963 Oakwood Road (both): 1963 Marley Creek: 1964 Jumpers Hole Road (both): 1971 Edwin Raynor Boulevard: 1969 MD 648H (both): 1971 Catherine Ave: 1971 MD 100 WB to I-95 SB flyover: 1970-1998 MD 100 EB over I-95: 1970-1997 MD 100 WB over I-95: 1970-1972 MD 10 SB: 1988 MD 10 NB: 1991 MD 295 (both): 1992 Wright Road: 1995 Harmans Road: 1995 MD 100Q W of MD 170: 1995 US 1: 1994 MD 100J E of US 29: 1992 Deep Run (both): 1996 Piney Run (both) E of MD 295: 1995 MD 713 (both): 1995 Stony Run (both) W of MD 170: 1995 Amtrak (both): 1995 MD 170 (both): 1995 Sawmill Creek: 1996 I-97 interchange ramps: 1996 MD 100 ramp over NB US 29: 1992 Small Stream east of MD 104: 1998 Tributary to Red Hill Branch E of Long Gate: 1993 Red Hill Branch east of tributary: 1992-1998 Snowden River Parkway (both): 1997 Old Montgomery Road E of MD 103 (both): 1997 MD 103: 1997 Executive Park Drive: 1999 CSX (both): 1996 Dorsey Station Access Road: 1996 MD 104: 1998 -->

Exit list

Auxiliary routes

MD 100 has fourteen auxiliary routes: five in Howard County, eight in Anne Arundel County, and one in both counties.