Uh, I think you are mixing terms, so I'm confused. The Union is usually used in opposition to The Confederacy and their essential argument was about the expansion of slavery into the western territories.

Sorry, up here we occasionally use it to refer to all of us States. Coney Island is also a chili-covered hotdog. :) -Note to self if I run for President.

I think if you sat down and made an honest list of the similarities and differences between Jim Crow style discrimination and prohibitions against same-sex marriage you'd see how different they were.

I have little doubt. But I see the effect upon same-sex couples as meaningful enough for the Federal government to clarify the Law-of-the-Land.

PS - Other forms of discrimination practiced by states: drinking laws, voting laws, property ownership laws, divorce laws, parental rights laws, right to open a business, etc, etc. All discrimination, all not federalized.

Yeah, some State laws preserve the State's interests and represent the will of their residents, and that's all well and good. But some run counter to our rights as US citizens. It's a complicated mess for sure. -It's a great out for politicians on the stump though.