Thanks for the info mmars, I got this bill about 45 years ago from a Gulf gas station (when they used to fill your car, wash the windows, check the tires and oil) back then they just kept a wad of cash in their pocket to make change. I removed a water dot or mark from the front of the bill and the paper was white under it so I knew it was real bill.
I could never find anything on it, not that I tried that often in 45 years, but now that I found your site and a couple of other folks who have a similar $1 bill some of the mystery has been answered. I was wondering, have you ever seen any other bill in any denomination with the same thing done to them?
Now that I think about it, this is the longest I ever held on to a buck … Lol. :-D