West Falls Church is a census-designated place (CDP) in Fairfax County, Virginia, United States. The population was 29,207 at the 2010 census. Before 2010, West Falls Church was officially named Jefferson. Outside of the Jefferson Village neighborhood, "Jefferson" generally is not used locally to refer to the area bounding Falls Church city to the south and southwest that comprises the CDP. Likewise, "West Falls Church" is rarely used to describe the area but is usually applied to areas west of Falls Church city or near West Falls Church Metro station. The bulk of it is made of subdivisions built in the 1940s and early 1950s, including Jefferson Village, Westlawn, Hillwood, Sleepy Hollow, Woodley, Raymondale and Broyhill Park.

Idylwood is a census-designated place (CDP) in Fairfax County, Virginia, United States. The population was 17,954 as of the 2020 census. It originally developed as a suburban community along the route of the Washington and Old Dominion Railroad, and later along Virginia State Route 7. The construction of the Capital Beltway in the 1960s, and I-66 and the Orange Line of the Washington Metrorail system in the 1980s, as well as the concurrent development of nearby Tysons Corner into Washington's leading suburban business district, led to the development of several apartment, townhouse, and small-lot single-family housing complexes, as well as the high-rise Idylwood Towers condominium, in the portion of Idylwood lying to the north of I-66. The area to the south of I-66 remains primarily large-lot single-family.