Just took myself on a little North American OSM adventure as a spinoff to alexz recent diary entry about lodging roads in Canada (http://www.openstreetmap.org/user/alexz/diary/12842).
Nice to see so much data in the US, but it struck me how you can actually see off the OSM data how well developed/organized/privileged a country is. It is really apparent when following the Mexican/US border that Mexico is only sporadically mapped, in contrast to the areas just over the border which has a lot more coverage.
An interesting spot is around the bi-national area El Paso/Ciudad Juárez at http://www.openstreetmap.org/?lat=31.78&lon=-106.14&zoom=8&layers=O (more info at http://en.wikipedia.org/wiki/El_Paso%E2%80%93Ju%C3%A1rez). Here some cross-border mapping has been done, but it doesn't stretch far into Mexico.
Being European having done no US-traveling at all, I don't know much about the Mexican/US tensions or conflicts. But from the map and geography I would reckon this whole area could be a rather interesting cultural exchange point.
Even though the mainstream press has it's focus on the very unsafe situation in Ciudad Juárez aka. City of the Dead (http://www.nydailynews.com/topics/Ciudad+Juarez), more local voices seems much more relaxed about this for the ordinary traveller(http://www.juarez-mexico.com/HTML/YourSafety/YourSafety.htm).
Think this area deserves a place on my 'want-to-visit' list.
Thank you to all OSM contributors for making this virtual adventure possible!