It used to be much worse -- a lot of the land grab was due to Arizona law years ago. But Tucson, as it has grown, has seen a lot of infill. Even so, places that look empty often have 1 per 3 acre housing.
Interesting, thanks for all the info! I've only been there once, and it the hills outside town were on fire at the time, but it still seemed like a cool neighborhood and cool town over all if you can handle the desert thing...