The US finally begins to crawl out of the third world

Before Civil Rights laws were passed in the US, citizens of differing races were often not allowed to marry, Such marriages were legally prohibited and not recognised by the state or federal governments. If someone suggested a law granting Interracial couples the right to "Civil Unions", rather than Marriage, It would be considered a policy of segregation or racial discrimination. It would be most enlightening to hear how discrimination by race in this regard is somehow different that discrimination on the basis of gender.