I just tal;ked to my brother who lives in Tucson - a pretty liberal guy - a schoolteacher.
He told me that the Tucson sector captures about 600K a year, a fraction that get across.
Last I was in Tucson, a couple years ago, I made the mistake of shopping in a wallymart. I thought I had entered a store in Nogalas Sonora or Naco. The checkers were bi-lingual - they spoke some English.....
Go to the YUMA Az Wal-Mart and they have to request an English speaker for you.