The first state to repeal its ban on interracial marriage was Pennsylvania in 1780. (The scream you hear is Rick Santorum who would surely have claimed it would lead to men marrying goats.) When Barack Obama was born in 1961, there were 22 states that would have considered his parents marriage a felony. Sixteen states - the eleven Confederate states plus Delaware, Missouri, Oklahoma, West Virginia, and Kentucky - saw their anti-miscegenation laws overturned by the US Supreme Court in 1967.
Marriage is one of the 'basic civil rights of man,' fundamental to our very existence and survival.... To deny this fundamental freedom on so unsupportable a basis as the racial classifications embodied in these statutes, classifications so directly subversive of the principle of equality at the heart of the Fourteenth Amendment, is surely to deprive all the State's citizens of liberty without due process of law. The Fourteenth Amendment requires that the freedom of choice to marry not be restricted by invidious racial discriminations. Under our Constitution, the freedom to marry, or not to marry, a person of another race resides with the individual and cannot be infringed by the State. ~ Chief Justice Earl Warren, Loving v. Virginia, 1967Southern states were slow to repeal their unconstitutional statues, the last was Alabama in the year 2000.
The anti-miscegenation laws were sometimes strangely complex. Several enforced the one-drop rule where a single drop of "Negro" blood defined a person as black. A person 99% white could not marry someone 100% white. In 1957, New Orleans created a "race list" of "historically Negro surnames" to double check all marriage licenses against lest a mixed marriage might slip by. For two decades an average of nearly 300 marriages a year were denied using this list. Source.
This latent fear of race mixing is one of the reasons Southern Republicans are so insanely hateful of President Obama. He is the product of the demonic union of an Negroid man and a Caucasian woman. To Southerners this was ingrained as a visceral fear and something to be prevented at any cost. Lynching was the frequent result of even the suspicion of miscegenation.
All this is caused by the Louisiana justice of the peace who has publicly, and proudly, stated he will not perform miscegenation weddings.