I doubt the Texas DOT would delve that for into it. I can probably buy a Yokogawa PLC and slap an American flag over it and no one would know the difference.
My local DOT specified Allen-Bradley because the local A-B expert lives about ten minutes on foot from the most active bascule bridge in the States. Fifteen if I have to row.
I think I have seen 'Made in Singapore' on some the AB MicroLogix PLCs I have bought. So... is that really American Made? I guess you are skirting the issue, which you probably have to, by choosing an American Company. So I agree with Ken Roach about meeting 'intent' with AB, but have a small issue with the 'letter' part as I work in manufacturing here in the US. I see our plants transfer products overseas for tax holidays and lower labor costs at a rapid pace.
I have never used any of their stuff, but EZAutomation says they are American Made of US and Foreign Components, or something like that (link).
do as you please but comments about avoiding AB because of poor relations with one distributor is silly. there are other distributors too, it is not set in stone that you must use those guys. personally, i would definitely go for popular brand - and in this case AB. i've seen other made in USA plcs but honestly, i can probably count all of them using my fingers (guess depends on industry you are in)