On June 30, 1922, a Washington policeman was at the Tidal Basin bathing beach measuring swimsuits. Well, more accurately, he was measureing the distance between knee and suit, after the Superintendent of Public Buildings and Grounds issued an order than suits not be over six inches above the knee.
With that in mind, here are some photos that show what beaches looked like
100 years ago. Compare these to today. A lot has changed since then.