Uncle Sam's was a disco nightclub chain in several US cities from the mid 70s to the late 80s.
There were clubs in Houston, Detroit, Providence, Levittown, Minneapolis, Buffalo, Des Moines, and Syracuse. At least. There were probably more.
Uncle Sam's - "Let's Spend the Night Together"
Shiny Happy Customers Night in Buffalo looks like fun.
Shot of the Minneapolis merch table in 1977. T-shirts cost $3.99!
This 70s Uncle Sam's t-shirt seems to be from 1976. It's in great shape and ready to do the hustle. Check it out at Skippy Haha Vintage Etsy now!