In 1920, to avoid confusion between Alexandria County and the City of Alexandria and to honor Robert E. Lee, the name of the County was changed to Arlington. That name was obviously derived from the Arlington Estate. It had long been made familiar by federal developments on the Arlington property: not only the Arlington National Cemetery, but also the Arlington Experimental Farm (1900-1940), and the Arlington Radio Towers (1913-1941). In 1921 the County was gaining new prestige from the attention focused on the dedication of the Tomb of the Unknown Soldier in the Arlington National Cemetery and from plans to construct the Arlington Memorial Bridge.

By 1930, the population of Arlington had increased to about 27,000. The advent of the automobile had facilitated access to the areas in the County located between the trolley lines. During this period the County’s several hamlets and commuter villages began to merge, in the process reshaping the County’s basic infrastructure and transportation lines. In addition to the villages referred to above, other areas included Lyon Village, Nauck, and Queen City. Arlington County was becoming a single, distinct community. In 1932 the old magisterial districts that had been established in 1870 were abolished, and the County government was integrated through the at-large election of a new County Board and the establishment in Arlington in 1932 of the first County Manager form of government in the United States. The County Manager was to be chosen by the County Board. The first County Manager was Roy S. Braden.

During the Depression and with the outbreak of World War II, the expanding federal work force created a demand for housing. Arlington’s farmland was soon filled with thousands of new homes as well as large garden apartment complexes, such as Colonial Village, Buckingham, Fairlington, and Arlington Village. Colonial Village, constructed between 1934 and 1940, was the first large-scale rental project to be approved by the Federal Housing Administration for mortgage insurance and became a model for similar developments throughout the country.

During World War II, the Washington, D.C. region was flooded with military personnel and civilian workers supporting the war effort. Arlington’s population doubled, and the County began to make the transition from a bedroom community to a place where large numbers of people worked. The Pentagon, which opened in 1943, employed more than 36,000 military and civilian workers. Arlington, along with jurisdictions across the entire Washington metropolitan area, also began the process of adapting to meet many new needs that, in addition to housing and public transportation pressures, included highways, schools, libraries, public health facilities, and recreation areas.