In the early 20th century, many Virginia Indians began to reorganize into official tribes. They were opposed by Walter Ashby Plecker, the head of the Bureau of Vital Statistics in Virginia (1912–1946). Plecker was a white supremacist and a follower of the eugenics movement, which had racial theories related to mistaken ideas about the superiority of the white race. Given the history of Virginia as a slave society, he wanted to keep the white "master race" "pure." In 1924 Virginia passed the Racial Integrity Act (see below), establishing the one drop rule in law, by which individuals having any known African ancestry were to be considered African, or black.