This amendment attempted to abolish interracial marriage and, for obvious reasons, we are very grateful it failed. Racist Democrats in the early 20th century enforced these laws around the country on a local level.
A Southern Democrat proposed the amendment after famous boxer Jack Johnson (who was black) married Lucille Cameron, a white woman. You might remember that name because recently President Trump posthumously pardoned Johnson a century after his racially-motivated arrest. This shameful episode sheds light on all that was wrong with the Democrat party at the time.