States · Virginia · Fairfax County

Union Mill, Virginia.

A community in Fairfax County, with no city government of its own. Zillow publishes no home prices for it: see Fairfax County’s.

Living in Union Mill, Fairfax County, Virginia

Union Mill, in Fairfax County, had 4,997 people in the 2020 census. 95% of its homes are lived in by their owners and 5% are rented. Unemployment in Fairfax County was 3.3% in August 2026, and the county had 0.3% fewer jobs in 2025 than the year before. The most residents work in professional services, then schools and health care.

People 4,997 in the 2020 census; median age 47.3
Household income Too few homes in Union Mill for the Census survey to measure.
Unemployment 3.3% Fairfax County, August 2026; 3.4% a year before
Homes 95% lived in by their owners; 5% rented
  • 1,416households
  • 71%of adults have a degree
  • 4%below the poverty line
  • 37 mintypical commute
  • 28%work from home

What residents work in

  • Professional and business services29%
  • Schools, hospitals and social care19%
  • Banks, insurance and property13%
  • Government9%
  • Shops (retail)8%
  • Restaurants, hotels and entertainment7%

Employed residents by industry, from the Census survey. Fairfax County had 634,638 jobs in 2025, 0.3% fewer than the year before (Bureau of Labor Statistics).

Weather through the year

Average daily high and low for each month: coldest in January, 42° and 24°; warmest in July, 88° and 69° 20° 40° 60° 80° J 42° 24° F M A M J J 88° 69° A S O N D
Average daily high and low for each month: coldest in January, 42° and 24°; warmest in July, 88° and 69° 20° 40° 60° 80° J 42° 24° F M A M J J 88° 69° A S O N D

Coldest in January, with highs near 42° and lows near 24°; warmest in July, with highs near 88° and lows near 69°.

Average daily high and low, 1991–2020, at the Manassas weather station, 7 miles away (NOAA).

Largest workplaces in Fairfax County

  1. Fairfax County Public SchoolsSchool district28,829FTE
  2. Inova Fairfax HospitalGeneral hospital11,085FTE
  3. George Mason UniversityUniversity or college6,112
  4. J & J Worldwide ServicesBase facilities operation support services3,025
  5. Northern Virginia Community CollegeTwo-year college2,762
  6. MTSI Modern Tech SolutionsDefense contract engineering services2,334
  7. Clark Construction GroupAddition, alteration and renovation for-sale builders, commercial and institutional building2,204
  8. Hilton Worldwide Holdings, Inc.Hotels2,186

Staff on average in 2025, as each workplace reported it to OSHA with its injury records: 664 workplaces with 20 or more staff, 129,174 people in all across the county; Union Mill has one of its own. School districts come from the Common Core of Data (NCES, 2023–24), hospitals from their Medicare cost reports (CMS, 2023) and colleges from IPEDS (NCES, 2023–24); FTE marks full-time equivalent staff. Not listed: many offices and banks, which need not report to OSHA; military bases, whose staff OPM withholds; and, in about half the states, city and county governments.

Natural hazards

  1. Inland floodingRelatively high
  2. Winter weatherrelatively high in parts of Union MillRelatively moderate

FEMA’s National Risk Index (December 2025) rates the risk each natural hazard poses to the people, buildings and farms in Union Mill’s census tracts, against the rest of the country; all of them together, relatively moderate. It is meant for planning, not a substitute for a local risk assessment or a flood map: FEMA’s index.

From the U.S. Census Bureau’s 2020 census and its American Community Survey (2020–2024 five-year estimates), and the Bureau of Labor Statistics. A survey, so each figure has a margin of error, and figures it is not sure of are left out. More on Fairfax County.