Capital Traction Company U.S. Mail Streetcar

Can anyone identify the location of this photo? It was taken in 1900, showing a United States mail car.

This U.S. mail streetcar, owned and operated by the Capital Traction Company, was used to process and transport mail in Washington, DC.
This U.S. mail streetcar, owned and operated by the Capital Traction Company, was used to process and transport mail in Washington, DC.

Source: Smithsonian

By the way, you should check out this awesome old film of a mail streetcar heading down Pennsylvania Ave. NW.