Our cherry trees in NE Ohio (further north than DC) were done about 1-2 weeks ago depending on the type of tree and tree situation (shadow, northern orientation, etc).
DC I believe has longer lasting trees but they typically start bloom in mid-late March and definitely should be done by now.
I tried searching many ways to get a photo from the end of April but no success so far.
The Tidal Basin forms part of the grounds that make up the National Mall. Here is a description of it, which includes a great aerial shot:
https://www.nps.gov/articles/dctidalbasin.htm
Here is a photo of cherry trees along the Tidal Basin: