If you want to enter Nogales, Mexico on foot, no one will stop you. Unlike Togo (where I waited nearly an hour for the border patrol to check my papers), no one stamped my passport as I walked through the metal turnstile and crossed the border.* These photos and my own memories are the only proof that I spent an hour in Mexico.
Oh, Mexico! I’ve never really been, so I don’t really know.
*Border agents did check my passport when I returned to the USA.