Loudoun County, Virginia, is the richest county in the United States. The average household earns $178,707 a year, according to the U.S. Census Bureau. Most of the richest counties are near Washington, D.C., Silicon Valley, or New York City, where many people work in government, technology, and finance.
The median household income in the U.S. reached $80,610 in 2023, up from $77,540 in 2022, according to Census Bureau data reported by U.S. News & World Report. Some counties earn more than twice the national average. This guide explores the 10 richest counties in the U.S., what makes them wealthy, and how they compare with others.
The 2025 data on the richest counties in the U.S. is still relevant in 2026 because Census estimates change slowly. These counties remain the wealthiest in the country, and the rankings have stayed almost the same for years.
What Is the Richest County in America?
Loudoun County has had the highest median household income among large U.S. counties since 2007. WorldAtlas confirms this ranking using the latest Census figures. Loudoun sits about 25 miles west of Washington, D.C. Its wealth comes from an unglamorous source: data centers.
Loudoun County has one of the world’s biggest data center hubs. Companies like Amazon, Google, and Verizon operate large facilities there, bringing in billions of dollars in tax revenue.
This money helps support excellent schools and public services. These benefits attract more tech workers and government contractors. Loudoun shows that the richest county in America is built on strong jobs and a stable economy, not just famous neighborhoods.
The Top 10 Richest Counties in America (Ranked by Income)
People searching for the top 10 richest counties in America usually want a simple ranked list. Below is the latest ranking based on median household income from the American Community Survey.
| Rank | Country | State | Median Household Income |
| 1 | Loudoun County | Virginia | $178,707 |
| 2 | Santa Clara County | California | $159,674 |
| 3 | San Mateo County | California | $156,000 |
| 4 | Falls Church (city) | Virginia | $154,734 |
| 5 | Fairfax County | Virginia | $150,113 |
| 6 | Howard County | Maryland | $146,982 |
| 7 | Douglas County | Colorado | $145,737 |
| 8 | Nassau County | New York | $143,408 |
| 9 | Los Alamos County | New Mexico | $143,188 |
| 10 | Marin County | California | $142,785 |
Note: Figures reflect five-year American Community Survey estimates and shift slightly with each annual Census update.
Santa Clara and San Mateo Counties, California
Santa Clara and San Mateo are the main counties of Silicon Valley. Apple and Nvidia are based in Santa Clara, while Meta, Oracle, and Visa have offices in San Mateo. High-paying tech jobs and stock bonuses keep both counties among the wealthiest in the U.S.
Falls Church, Fairfax, and Arlington, Virginia
Washington-area communities earn strong incomes from federal government jobs. Many people also work in defense contracting and consulting. Although Falls Church is an independent city, not a county, it still ranks among the top five wealthiest areas in the country.
Howard County, Maryland and Nassau County, New York
Howard County is located between Baltimore and Washington, D.C. It has many biotech and cybersecurity companies. Nassau County is near New York City. Many people who work in finance live there, and it is known for its expensive homes.
Douglas County, Colorado; Los Alamos County, New Mexico; and Marin County, California
Douglas County is wealthy because of the rapid growth of Denver’s suburbs. Los Alamos County earns most of its income from its national laboratory, showing how one major employer can support a small local economy. Marin County, across the bay from San Francisco, is known for its mix of long-established wealth and newer income from the tech and finance industries.
Why Are These Counties the Wealthiest in the U.S.?
A few key factors make these counties the richest in America. Most depend on one or two major industries instead of many different businesses.
- Government and federal jobs: Loudoun, Fairfax, Falls Church, and Arlington are close to Washington, D.C. Many people earn high salaries from government, defense, and consulting jobs.
- Technology companies: Santa Clara and San Mateo are at the center of Silicon Valley. Many workers receive stock compensation, which can greatly increase their income.
- Finance jobs: Nassau County is close to New York City. Many bankers and business executives choose to live there while working in the city.
- Research and science: Los Alamos County depends mainly on one large employer, the national laboratory. This shows how one organization can support a local economy.
- Growing suburbs: Douglas County and Howard County are near large cities. New homes and strong job markets attract many high-income families.
Notice what’s not on the list: inherited wealth or old family money. These counties rank high because people earn high salaries, not because they inherited wealth.
Richest Counties in the U.S. Map: Where the Wealth Clusters
When you look at these 10 counties on a map, a clear pattern stands out. Most of them are located near three major metro areas. The Washington, D.C. region includes Loudoun, Fairfax, and Falls Church. The San Francisco Bay Area includes Santa Clara, San Mateo, and Marin. The New York metro area includes Nassau County.
The other two counties are in the western U.S. Douglas County, Colorado, and Los Alamos County, New Mexico, are wealthy because of strong local industries instead of being part of a large metro region.
This shows that most of America’s richest counties are close to major job markets on the coasts or near the nation’s capital. Very few are in the Midwest or the Deep South, where household incomes are generally closer to the national average.
Richest Counties in America vs. Richest States
A county’s income does not always match its home state’s overall ranking. Virginia, for example, rarely ranks among the richest states in America on a statewide basis. Yet it holds three of the ten wealthiest counties in the country.
The opposite pattern appears in New Mexico. Los Alamos County posts a six-figure median income, even though the state as a whole ranks closer to the poorest states in America.
This gap matters for anyone comparing cost of living or relocation options. A state’s average tells you little about what a specific county actually pays or costs.
How Many of America’s Counties Are Actually This Wealthy?
The United States has more than 3,000 counties and county equivalents, ranging from the biggest states in the USA to the smallest. According to the latest U.S. Census data, only about 149 counties have a median household income above $100,000. That means fewer than 5% of all U.S. counties reach this level, making the top 10 richest counties truly stand out.
Richest Counties in the U.S. per Capita vs. Median Household Income
Most lists of the richest U.S. counties use median household income because it shows what the average family earns. Some people, however, look for per capita income rankings, which measure income in a different way.
Kiplinger’s cost-adjusted ranking takes yet another approach. Even after this adjustment, Loudoun County ranks first, earning more than $23,000 a year above the second-place county.
Per capita income is the average income for every person in a county, including children and retirees. In smaller counties with many wealthy residents, this number can be higher even if the median household income is lower. Both measures are useful, but median household income is the most common way to compare counties.
Richest Counties in the U.S.: 2025 vs. 2026 Data
The rankings change a little each year, but the top counties usually stay the same. In the 2025 ACS estimates, Loudoun County ranked first with one of the highest median household incomes. The 2026 update kept Loudoun in the top spot and showed its income had increased even more. Santa Clara and San Mateo counties also remained in second and third place.
This helps people compare counties over time. Most counties that rank in the top 10 stay there every year. Compared with the richest U.S. counties in 2025, this year’s rankings show small income increases instead of major changes.
Conclusion
Loudoun County is the richest county in the United States. It is followed by counties in Silicon Valley and the suburbs around Washington, D.C. This shows that the highest incomes are found in only a small number of U.S. counties. Even after considering the cost of living, Loudoun remains the richest. A wealthy county does not always mean the entire state is wealthy.
FAQs
- Is Loudoun County the richest county in America?
Loudoun County, Virginia, has had the highest median household income among large U.S. counties since 2007. Today, it stands at $178,707.
- What’s the richest county in America right now?
Loudoun County is the richest county in the United States, according to the latest U.S. Census data. Santa Clara County ranks second, followed by San Mateo County in third place.
- Is Fairfield County the richest county in America?
Fairfield County, Connecticut, includes wealthy areas like Greenwich. However, its overall median household income is lower than Loudoun, Santa Clara, and several other counties on this list.
