First there were uniforms -- athletic, Scout, military -- that showed you were a member. Then came letter sweaters and badges to sew on them: you'd not only been there, but done something. We like to be identified by our clothing; indeed, the messages we wear on our T-shirts often speak for us. As souvenirs, they replaced engraved spoons and scarves with state maps. A shirt proclaiming "Fort Lauderdale, Spring Vacation 1979" made you feel special. Today, nearly every town, organization, sports team, company and school has its shirts. No longer do firms pay people to wear sandwich boards advertising their wares; instead, consumers spend their own money to buy shirts, and other items, that tout favorites: Budweiser, I heart New York, Pac-Man or Surf Naked. However, you can no longer be sure that the wearer actually went to the University of Hawaii or played soccer for Braddock Road Youth Club or drinks Dr. Pepper. So it goes with silk-screened shirts that a White House staffer has created. The Press Corps Store, run by the Reaganite's wife and a friend, has shirts designed for those who accompanied President Reagan on his trips. Among them are a yellow number tracing the president's route in red across Europe, and another commemorating the Economic Summit at Versailles with seven national flags in color and the words in French. The shirts were reportedly snapped up by staffers and pressies. After all, in this county of the common man, what's more elite than being a member of the First Entourage? But, surprise! These statements of in-group-ism are available to anyone. Price range: $7 for a navy shirt featuring the White House and the words, "White House Press Corps," to $9 for the five-color Economic Summit shirt. Most recent is a shirt from Vice President Bush's tour to the Orient and Australia. Most models are heavyweight 100 percent cotton Hanes Beefy-T shirts in small, medium and large adult sizes. The Press Corps Store, Box 1537, Vienna, Va. 22180. 281-0566. S, M, L adult sizes.