The Peirce Mill on Tilden Street near Beach Drive was already an historic landmark when postcard photographer Willard R. Ross took this photo on July 18th, 1909.
This photo is from the Willard R. Ross Postcard Collection at the DC Public Library, digitized and available online at DigDC.DCLibrary.org.
According to the library, Ross was born in 1860 and moved to DC around 1910. He became a postcard photographer specializing in “hometown” views.