There is no real legal or political path to independence. That was pretty much settled in 1865. It's also not that popular, states and cities are heavily dependent on federal gibs. I think it could only happen if the federal government became so weak they could do nothing about it, which could happen when the globohomo megacorps chip away at federal sovereignty, the dollar becomes worthless, and the gibs dry up. Maybe counties seceding to other states, like Greater Idaho or most of Virginia seceding to West Virginia is more viable.