Why did they stay in Washington, D.C. after graduation?
We got to see only Wendy's (Mare Winningham) family who lives in Washington, D.C. or in Maryland or Virginia within the Beltway (I-495).
I thought it was strange they all decided to stay in Washington, D.C. after graduation to make their lives. Were the rest from the D.C. area like Wendy? I thought that most Georgetown students were residents (i.e. from around the country who lived on campus and not locals or "commuters").
Since he loved politics, I could see Alec (Judd Nelson) staying in Washington, D.C. Since Leslie (Ally Sheedy) was in love with him, staying made sense. Billy (Rob Lowe) had a wife and kid to support (to the extent that he did). At the end, he does leave to make his way in New York. Wendy (Mare Winningham) obviously had her family in the area. Since Dale was in the area, Kirby (Emilio Estevez) trapped himself. It would be interesting to see if he does stay after he gives up on Dale.
But Kevin (Andrew McCarthy) would have done better in New York as a journalist/writer. Jules (Demi Moore) might have done better in New York or Los Angeles.
Most, if not all, cliques break up after graduation (high school or college). Some people choose to go home (to work or continue their education and be near their families), others go to other cities (for work or education). Some would stay in the city where they went to school such as NYC, LA, Boston, or Washington, D.C. if there were opportunities. But that everyone would do that didn't seem believable (unless there were others in the clique who did leave).
At the time, email was in its infancy (on Compuserve and Prodigy) and the Internet, as we know it, didn't exist. Today, through email and social networking sites, it's probably easier to maintain cliques (assuming the members don't get tired of each other or simply outgrow certain people).