I saw something like that at Dulles airport about 20 years ago.  It was 
about the same time of day, but don't remember the season.  I wasn't a 
birder then, but it made a big impression anyway.  A stream of birds 
from horizon to horizon!

	Bob Hartman
	Colesville, MD

Monroe Harden wrote:
> While driving to and waiting for the start of our Harford Bird Club woodcock
> viewing last night, we saw a huge flock of blackbirds flying in a
> west-southwesterly direction in Aberdeen.  It was a large stream of birds
> that continued for about 30 minutes, like a big black tube in the air.  I
> can't begin to estimate how many thousands of birds were there.  The flock
> was visible from about 5:20 until 5:50 or so.