She is a native of Pennsylvania, Ohio or Southern California, but attended university on the east coast - typically a larger school with a Division I sports program and rigorous, but not too tough academic standards - Examples would be James Madison University, Penn State, College of Charleston, or University of Rhode Island. During college Arlington girl was a sister of Delta Gamma or Kappa Alpha Theta sororities.
When she didn't find a husband during college, she moved to Washington, DC because Daddy couldn't afford to buy her a condo in NYC or because the college boyfriend (an engineering or accounting major) has a job in DC.
Arlington girl works exactly 40 hours a week, spending much of that time at anntaylorloft.com or bananarepublic.com. After work she goes to many happy hours in downtown washington, drinking several $15 martinis while trying to meet Mr. Right. Sometimes, when her "allowance" from daddy is running low, she goes to dollar draft night at Rock Bottom Brewery in Ballston.
She lives in a 1 bedroom apartment or has recently secured a condo or townhouse with Daddy's generous help on the down payment. The apartment is filled, painstakingly, with Pottery Barn furniture, but the refrigerator is empty - except for leftovers from dinner out 3 nights ago.
Arlington girl will live in Arlington until she: a) gets married and moves to a McMansion in Fairfax county or b) turns 30 and is still single - then she'll get her MBA from George Mason or George Washington and move to New York.
Arlington girl may also make appearances in gentrified and gentrifying sections of Washington DC - like Eastern Market and other areas of Capitol Hill. The distinguishing factor between Arlington girl and Capitol Hill girl is that Arlington Girl makes 2-3 times as much Capitol Hill girl and therefore is not prostituting her self like Jessica Cutler.
See also marina girl or trixie for her San Francisco and Chicago counterparts