Ax, ya the cacti area was near Tehaucan, and I saw from my journal that we passed from Oaxaca state into Puebla state that day.
like I said before, I'd love to return to Mexico and explore some other non touristy places.
One other memory of Pachuca, I'm pretty certain that I never saw another gringo while there. Nice traveling in non touristy places. When I got to San Miguel de Allende, holy kajeepers, elderly gringo central ! And lots of Mexican tourists too, just such a shock after being in little towns and villages nearly all the time.