From its beginnings, Maryland's attitudes towards African-Americans were vaguely hostile. The 1715 state constitution enforced slavery, although Maryland was never a large slave-holding state; racist attitudes continued into the 19th century, when Know-Nothingism took firm root in the state.  During the Civil War, Maryland was divided between its slave-holding, which naturally allied it with the Confederacy, and its proximity to Washington, DC, which made it remain in the Union. A local publication noted, however, that "most Prince George's loyalties were with the Confederacy" and that the County seat newspaper "was denied use of the U.S. mails because of its Southern leanings."  When a new State constitution that abolished slavery was sent to Maryland voters in 1864, the state as a whole only narrowly approved it; however, Prince George's County decisively rejected it, 1,293 votes against to only 149 for. 
The years following World War II were years of unprecedented growth for Prince George's County. The population more than doubled from 1940 to 1950 and more than tripled from 1950 to 1970.  By 1970 the county's population of 660,000 was the second largest in the Washington metropolitan area, second only to the District of Columbia. The black population, after a decline at the turn of the century, was also on the rise, and by 1970 55% of all Washington-area suburban blacks lived in Prince George's County.  Although the county's blacks and whites were "generally more alike socioeconomically than blacks and whites in any other major Washington suburb," they tended to live apart from each other.  This separation in housing can be attributed in large part to the practices of "blockbusting," in which white homeowners are persuaded to sell their homes at a loss by being told that blacks are planning to move into the area, and "steering," in which prospective white home buyers are steered towards homes in white neighborhoods and prospective black home buyers are steered towards homes in black neighborhoods. These practices continued throughout the first half of the 20th century; as Gary Orfield wrote, "Only in the late 1960s did the Department of Housing and Urban Development begin to act against segregation in public housing."  By that time the impact on the racial composition of the county's public schools had already been made.