Drive through Nogales
Nogales certainly isn't the poorest place I have ever been, but I don't think I've ever seen so many people living in such miserable conditions. Shacks with tin roofs and old pallets for walls were pretty common. Maybe an old snow fence to keep the chickens in the yard. The people don't seem to care...they would rather take their two hour siesta than fix up their little corner of hell.
Nogales lies on the US-Mexican border just south of the US's Nogales, AZ. When visiting from the US, you can either park on the US side of the border and walk across, or drive as far as 12 km into Mexico's "free zone." If you decide to go beyond the free zone, you must have extra insurance on your vehicle for Mexico, and you must stop at a border control area to register your vehicle (which seems to take 3-4 hours in this corrupt bureaucracy).
The population of Nogales, Mexico, is about 160,000 and growing quickly due to benefits of NAFTA.
Drive through Hermosillo
Hermosillo is another stop on the way from Nogales to San Carlos...and it's another dirty little town. If you take the libro road instead of the toll road, you will see much more of this little Mexican paradisio.
Hermosillo is the capital of the Mexican state of Sonora in the Sonoran Desert. This is a large city with about 700,000 residents, the largest employer being Ford Motor Company which produces 300,000 cars a year here.