At Thoreau's Walden Pond, in Concord, Massachusetts. Yup, the sign really does say: "bathing suits for rent." (Click image to see a larger version.)
Photo by Edwin Locke, 1937. [American Memory link]
Showcasing some of the 160,000 images taken between 1935 and 1944 by government-hired photographers. (If you were to look at 100 of them per day, every day, you'd need more than four years to view them all).