U.S. Route 240

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U.S. Route 240 was a United States Numbered Highway that historically connected Bethesda, Maryland and Frederick, Maryland, serving as a principal arterial linking suburbs, federal institutions, and regional corridors. Initially designated in the 1926 United States Numbered Highway System plan, it provided a through route between the Capital Beltway approaches near Washington, D.C. and the western Maryland communities near the Catoctin Mountain Park entrance. The route influenced development patterns around Rockville, Maryland, Gaithersburg, Maryland, and facilitated access to landmarks such as the National Institutes of Health, Walter Reed Army Medical Center, and the National Mall via connecting roads.

Route description

The corridor began near Bethesda Row and proceeded northwest along roadways that paralleled the Washington Metropolitan Area Transit Authority corridors and connected to the Rock Creek Park approaches. It traversed suburban centers including Chevy Chase, Maryland, Friendship Heights, and Silver Spring, Maryland, intersecting with arteries such as Connecticut Avenue (Maryland), Wisconsin Avenue, and the I-495 (Capital Beltway). North of Rockville Town Center the alignment passed through Montgomery County, Maryland woodlands and suburban developments adjacent to Great Falls, Virginia viewsheds and reached Gaithersburg before ascending the Catoctin Mountain foothills toward Frederick County, Maryland communities like Brunswick, Maryland and Emmitsburg, Maryland by connection. The corridor linked to long-distance routes including U.S. Route 15, U.S. Route 40, and provided access toward Interstate 70 and Interstate 270 interchanges that serve the National Institutes of Health research campus and the Walter Reed National Military Medical Center.

Designated in the national plan promulgated by the American Association of State Highway Officials and the Bureau of Public Roads in 1926, the route reflected early 20th-century priorities tying the District of Columbia to western Maryland market towns and federal facilities. Construction and improvements in the 1930s and 1940s involved agencies including Maryland State Roads Commission and drew on New Deal programs administered by the Civilian Conservation Corps and the Public Works Administration for bridging and grading near Rock Creek. Postwar suburbanization in the 1950s accelerated upgrades, with planning by the National Capital Planning Commission and funding influenced by acts such as the Federal Aid Highway Act of 1956, connecting the route to the nascent Interstate Highway System through spurs to I-70 and I-270. By the 1970s and 1980s, jurisdictional reassignments occurred involving the Maryland State Highway Administration and county governments, prompted by shifting traffic to parallel freeways like Interstate 270 and U.S. Route 15 realignments around Frederick. Sections were renumbered or decommissioned in the late 20th century during statewide route rationalizations undertaken by the Maryland Department of Transportation.

Notable historic junctions along the corridor included intersections with federal and regional facilities and routes: the approaches to Wisconsin Avenue (MD 355), crossings at I-495 (Capital Beltway), junctions with I-270 (Maryland) near Gaithersburg, connections to U.S. Route 15 north of Frederick, and interchanges serving U.S. Route 40 and US 40 Alternate toward Hagerstown, Maryland. It met arterial streets providing access to the National Institutes of Health campus, the Bethesda Naval Hospital complex, and commuter railheads on the Maryland Area Regional Commuter (MARC) network at Rockville station and Gaithersburg station. The corridor historically linked to parkways and scenic byways including the Catoctin Mountain Scenic Byway approaches and feeder roads toward Monocacy National Battlefield and Antietam National Battlefield via connecting routes.

Associated alignments and spurs included state-maintained successors designated by the Maryland State Highway Administration, local arterials that inherited old alignments in Montgomery County, and connections to federal routes like U.S. Route 15 and U.S. Route 40. Transit-oriented developments along the corridor were served by the Washington Metropolitan Area Transit Authority lines and by commuter rail service from MARC Train operations on the Brunswick Line. Nearby parkways, such as the George Washington Memorial Parkway across the Potomac and the Baltimore–Washington Parkway, provided complementary long-distance access, while regional planning involved entities including the Metropolitan Washington Council of Governments and the Maryland-National Capital Park and Planning Commission.

The former alignment influenced suburban growth patterns in Montgomery County, Maryland and Frederick County, Maryland, shaping commercial centers in Bethesda, Rockville, and Gaithersburg and supporting institutions like the National Institutes of Health and military medical centers. Its corridors became corridors for Metro (Washington Metro) expansion planning, regional transit studies by the Federal Transit Administration, and bicycle and pedestrian improvements coordinated with National Park Service management of parks such as Rock Creek Park. The route’s evolution reflected broader transportation trends including the rise of the Interstate Highway System, modal shifts addressed by the Transportation Research Board, and land-use changes overseen by the U.S. Department of Transportation and state planning agencies. Remnants of the designation persist in local road names, historic maps archived by the Library of Congress, and preservation discussions involving the Historic American Engineering Record and local historical societies in Montgomery County Historical Society and Frederick County Historical Society.

Category:United States Numbered Highways Category:Roads in Maryland