The problem with the US balkanizing is that there's not really any such thing as a 'red state' or a 'blue state'. Every 'red state' has some blue cities, and every 'blue state' has some red rural areas. Pretty sure California has more Republican voters than any state except Texas. So partitioning on state lines doesn't really work. Maybe over time people could migrate, but using South Carolina as an example, the two largest cities in the state would largely have to empty out. The state would cease to function.