Here, Gallup provides data from 1958 to 2007.
And here's a website dedicated to Loving Day, named 1967 Supreme Court decision Loving v. Virginia, which ruled that restricting interracial marriage was unconstitutional.
And here's a quote from the proposed constitutional amendment that would have prohibited interracial marriage:
"That intermarriage between negroes or persons of color and Caucasians or any other character of persons within the United States or any territory under their jurisdiction, is forever prohibited; and the term 'negro or person of color,' as here employed, shall be held to mean any and all persons of African descent or having any trace of African or negro blood. "Congressional Record, 62nd Congress, 3rd session, Dec. 11, 1912. Vol 49, p. 502
