On September 20th, 1664, Maryland enacted the first anti-interracial marriage law, also called an anti-amalgamation or an anti-miscegenation law. To amalgamate essentially means to to mix or make into a combination.

Maryland was one of the first thirteen colonies to be established in what is now known as the United States of America. One hundred and twelve years prior to America claiming its independence from British rule, Maryland enacted a law that was intended to prevent the intermarriage of Black men and English women. Subsequent to the passing of this anti-amalgamation law in Maryland, similar laws were passed in Delaware, Massachusetts, North Carolina, Pennsylvania, South Carolina, and Virginia.

During the colonial era, interracial marriage was a fairly common practice among white indentured servants and black slaves, as their daily lives and struggles were quite similar. They worked side-by-side from dawn until dusk. They resided together in the same dwellings, and they spent what little down-time they had consorting with one another. They often married and reproduced, thus creating an abundance of mulatto children. This began creating problems, because the strict lines of black and white were beginning to blend and become blurred. This was seen as something that could potentially pose problems in the future, especially in keeping well-defined boundaries between black and white.

Anti-amalgamation and anti-miscegenation laws were ultimately declared unconstitutional in 1967, in the landmark civil rights case of Loving v. Virginia (388 U.S. 1). In 1958, after marrying in the District of Columbia, Mildred Loving, a black woman, and her white husband were indicted by a Virginia grand jury for violating the state's anti-miscegenation laws. In January of the following year, both pled guilty and received a one-year sentence, which was suspended, pending their agreement to leave the state and not return for a period of twenty-five years.

Mildred Loving and her husband appealed that decision to the United States Supreme Court. The Supreme Court struck down the Virginia law (and similar laws in other states), and recognized that marriage was one of the basic civil rights known to mankind. Although the Supreme Court declared these laws unconstitutional, many of them remained on the books despite the fact that they were unenforceable. In 2000, Alabama became the last state to repeal a law banning interracial marriage.