Drivers license requirements going state to state

Thunder Mountain wrote:
The Drivers License is kind of like your marriage license. If you are legal in your state you are legal in the rest. But you need to pay attention to speed, length, weight restrictions, etc.

Not to muddy the water, but I think there were some issues with same gender marriage licenses having validity in states that didn't acknowledge the union itself. At least it used to be, but maybe things have changed. I don't pay much attention.