In the United States, racial segregation is the systematic separation of facilities and services such as housing, healthcare, education, employment, and transportation on racial grounds. The term is mainly used in reference to the legally or socially enforced separation of African Americans from whites, but it is also used in reference to the separation of other ethnic minorities from majority and mainstream communities. While mainly referring to the physical separation and provision of separate facilities, it can also refer to other manifestations such as prohibitions against interracial marriage (enforced with anti-miscegenation laws), and the separation of roles within an institution. Notably, in the United States Armed Forces up until 1948, black units were typically separated from white units but were still led by white officers. Signs were used to indicate where African Americans could legally walk, talk, drink, rest, or eat. The U.S. Supreme Court upheld the constitutionality of segregation in Plessy v. Ferguson (1896), so long as "separate but equal" facilities were provided, a requirement that was rarely met in practice. The doctrine's applicability to public schools was unanimously overturned in Brown v. Board of Education (1954) by the Supreme Court under Chief Justice Earl Warren. In the following years the Warren Court further ruled against racial segregation in several landmark cases including Heart of Atlanta Motel, Inc. v. United States (1964), which helped bring an end to the Jim Crow laws. Racial segregation follows two forms. De jure segregation mandated the separation of races by law, and was the form imposed by slave codes before the Civil War and by Black Codes and Jim Crow laws following the war. De jure segregation was outlawed by the Civil Rights Act of 1964, the Voting Rights Act of 1965, and the Fair Housing Act of 1968. De facto segregation, or segregation "in fact", is that which exists without sanction of the law. De facto segregation continues today in areas such as residential segregation and school segregation because of both contemporary behavior and the historical legacy of de jure segregation. History Reconstruction in the South Congress passed the Reconstruction Acts of 1867, ratified the Fifteenth Amendment to the United States Constitution in 1870, granting African Americans the right to vote, and it also enacted the Civil Rights Act of 1875 forbidding racial segregation in accommodations. As a result, the presence of Federal occupation troops in the South assured that black people