moisheh is right. There is the 'Free Zone' and then there is the 'Hassle Free Zone' and the rules are different for each. The Free Zone was established by the Feds and covers the whole length of the border and down to about 200 miles in most places. The Hassle Free zone was set up by the Sonoran Gov't and covers the entire state to entice travelers to come to their state.
FYI, PP is about 60 miles from the border and Kino is about 240 miles from the border (these are highway miles, not as-the-crow-flies miles).
To really confuse the issue, there used to be a "Sonora Only" but I think it morphed into the "Hassle Free Zone"
I can't guarantee any of this is what you'll face at the border though. They started playing around with the different zones a few years ago and it seems that every agent on the border has a different interpretation of the rules or is working from a different revision.
If anyone has a different understanding of this please let me know.