Been in Fairfax County for over 30 years.
On balance, highly educated, always at the top of the wealth chart, very transient and the home of:
The Beltway Bandits.
Highly dependent of Federal Gov’t spending.
They were private institutions doing research of all kinds for all sorts of contracts ~ probably most of them with private sector organizations.
Education and medical science are major employers ~ plus computer service companies. The internet began here (Remember UUNet), and other communication services are all over the place.