Yes, unlike other areas, DC's population is much more transitional given the dynamic nature of the federal government and the fact that the younger, sports-minded population (from which DCSki takes its roots) tends to move much more frequently.
Wonder if you take the members who originally signed up in 1999, how many of them are still in the area. Bet not many...
I hate to challenge some myths, but I'll bet DC is not as transient as it's made out to be, especially when compared to other urban areas.
From DCSki User List, taking only people who've posted more than 10 times and registered during the first three years. (Any less than 10 posts means they've never gotten traction on this site.)
Poster - # posts - register date ('scuze the formatting)
Scott 642 10/10/99 12:00 PM
lbotta 465 10/18/99 12:00 PM
Packyderm1 32 11/08/99 12:00 PM
Otto 134 11/19/99 12:00 PM
Jim 236 11/22/99 12:00 PM
ishaffer 13 12/29/99 12:00 PM
chuckie 67 12/29/99 12:00 PM
JohnL 1379 01/06/00 12:00 PM
Roy 610 01/11/00 12:00 PM
snobrdr 11 02/04/00 12:00 PM
twin58 185 04/01/00 12:00 PM
Gill 28 06/23/00 12:00 PM
MichaelB 49 11/20/00 12:00 PM
mrhazmat 47 12/07/00 12:00 PM
Chad 219 12/12/00 12:00 PM
AirHawk 55 12/27/00 12:00 PM
Finsout 21 01/23/01 12:00 PM
Mo 15 03/26/01 12:00 PM
johnfmh 1775 07/18/01 12:00 PM
myrto 212 10/04/01 12:00 PM
ski_guy_59 222 11/09/01 12:00 PM
PhysicsMan 220 11/20/01 12:00 PM
dtqjr 15 12/05/01 12:00 PM
kennedy 722 12/08/01 12:00 PM
JoeSoccerFan 12 12/19/01 12:00 PM
Lietmotiv 113 12/31/01 12:00 PM
Lot's of familiar names on the list, especially since we are talking about 6-8 years ago. How would a comparable sample in Boston MA, Cleveland OH, Denver CO, Kansas City MO, Charlotte NC or other areas stack up?