Final answer:
The one-drop rule reinforced racial segregation and upheld white supremacy by denying mixed-race identities. Although no longer legally enforced, its legacy affects racial identification and social dynamics in the U.S. today.
Step-by-step explanation:
The effects of the one-drop rule, which declared that any person with a single drop of black blood was classified as black, were profound and long-lasting. These rules surfaced at the height of the Jim Crow era, and included various laws such as the Virginia's Racial Integrity Act of 1924. These rules enforced racial segregation and restricted the rights of those with any African ancestry, effectively creating a system where racial purity was legitimized and mixed-race identities were not acknowledged.
The one-drop rule had significant social implications, reinforcing a binary notion of race that dismissed the complexity of multiracial identities and enforced the idea of white supremacy. It also influenced legal definitions of race and was used to justify discriminatory practices across various institutions, including marriage laws and segregation in the military. Despite the one-drop rule being legally defunct, its impacts are visible today in societal tendencies to fit people of mixed ancestry into single racial categories, especially for those with African heritage.
Blood quantum rules, reminiscent of the one-drop rule, still persist in determining membership in some American Indian tribes. While changes have occurred, with the 2000 census allowing people to identify with more than one race, the legacy of these laws still affects racial dynamics and identity politics in the United States.