San Antonio, TX (Precancel Or Post-Cancel?)

My instinct tells me this is probably a post-cancel, but it looked to be a bit interesting so thought I'd post it just to be sure. While the overprinting is quite light, the first "O" in "ANTONIO" really looks like a "U", I guess it's just poor inking:

Looks like a box cancel with the bar on the bottom perforations.

I agree. Thanks for confirming it for me.

Actually, I think I'm going to start a small collection of these stamps with post-cancels that look very close to resembling precancels. A lot of interesting styles and towns are represented. I don't know how many post offices actually used them, but I'm finding loads of them from every corner of the country. If nothing else, it will make for an interesting geography lesson.