Zip Code 22042 Cities. 22042 is located in the state of Virginia in the Washington D.C. metro area. Zip code 22042 is primarily located in Fairfax County. The official postal service name used for 22042 is FALLS CHURCH, Virginia.Portions of the 22042 zip code are contained within or border the city limits of Jefferson, VA, Annandale, VA, Merrifield, VA, Idylwood, VA, Falls Church, VA, and Lake Barcroft, VA.ip Code 22042 Politics. 22042 is located in the state of Virginia in the Washington D.C. metro area. Zip code 22042 is primarily located in Fairfax County. The official postal service name used for 22042 is FALLS CHURCH, Virginia.