In California, we used to get a free cup of coffee at Sambo's, or any of several other restaurants, if we showed the waitress our ballot stub, indicating that we had voted.
Around the mid to late 70s, even that was outlawed completely.
Since we moved out of the state in 1984, can't say if it's still that way or not...but it is here in SD.
Didn’t they outlaw “Sambos” too? They had to change their name, as I remember.