D.C. dance marathon, April 20, 1923. Click photo to enlarge.
The first US dance marathon was held just three weeks earlier in New York City where 32-year-old Alma Cummings was the last dancer to quit. She went through 6 dance partners in the 27 hours she was on her feet, igniting a marathon craze that swept the nation.
Dance marathon at the Venice Beach (California) Pavilion c 1923.
Click and scroll down to 1923 for more on the first American dance marathon.