The District of Columbia has critical information online, such as the very consequential fact that no one will be allowed to cross Pennsylvania Avenue between the Capitol Building and Rock Creek Park. That could be very disconcerting to Virginians who work downtown.

I'm impressed that in this basic document they also stress the use of area bike paths (for bikes and walking, not cars).

http://ddot.dc.gov/ddot/frames.asp?doc=/ddot/lib/ddot/information/pdf/brochure_emergencytips.pdf