The Mexican government has an agency called the Instituto Nacional de
Estadistica, Geografia e Informatica (INEGI). They have incredibly
valuable inofmration on the Mexican census, central bank statistics and
most importantly geography.
I have places a link in the Digital Maps section of the links to the
site. The site is interactive so you can add or subtract layers, zoom
in or out, etc.
Basically you can make custom maps, showing roads, relief, bodies of
water, climate, etc. It is pretty cool:
http://galileo.inegi.gob.mx/website/mexico/default.htm?sistema=1&c=423&s
=geo&md=d