Martin Austermuhle found this 1945 advertisement from DC’s Capital Transit Company, the operator of the streetcars. It makes a familiar point:
Read enough about transit and you will almost surely come across a reference to this image, or a variant, from the planners in Münster, Germany. It shows the street space occupied by 60 people in cars, on bicycles, and on a bus.
Clearly, this isn’t a new argument. But it’s taken a while for it to gain traction with many state, county, and city departments of transportation. In fact, DC (and many other cities) ultimately made the very tradeoff Capital Transit was hypothetically warning about: we did replace that streetcar with all those cars, to great harm.