Well she already left him so no way he can leave her.

Mother-in-law

why should that be sad??

Typically, there's supposed to be some sort of border control/authority at crossings. But the OP's mom could have had their passport and simply walked across which is pretty common for American citizens. Heck even my grandma has made a trip to Mexico that way. (Not sure if it's as easy for a Mexican citizen$

All you need is a passport book or card for Americans. They even have one that is specifically just for crossing the Mexican and Canadian borders. So long as that's all in order, I don't get the problem.

Yeah, whenever I cross the border they just look at my passport and wave me through. She probably just showed them her passport and they let her through.

i dont understand why that would be sad

Yea, all you need is a birth certificate and I.D.

#14: I think they meant, as a joke, on TOP of the car.

So citizens can't come back home once they leave?

And the border checkpoints all have walls, or at least chain link fences. They suck and my fat ass can climb over them in less than a minute, but they're there.