Surprise: America’s wealthy like warm weather and low taxes. That’s the takeaway from IRS data, analyzed by Forbes, on moves between counties. We looked for counties that the rich are moving to in big numbers. 
 
 Topping the list: Collier County, Fla., which includes the city of Naples. Tax returns accounting for 15,150 people showed moves to Collier County from other parts of the country in 2008, the latest year for which IRS data is available. Their average reported income: $76,161 per person–equivalent to $304,644 for a family of four. Although slightly more taxpayers moved out of Collier County than into it, the departing residents’ average income came out to just $26,128 per person. 
 
 Interactive Map: Where Americans Are Moving 
 
 Slide Show: Where America’s Rich Are Going (And Leaving) 
 
 Households that moved to Collier County principally came from other parts of Florida, with Lee, Miami Dade, Broward, Palm Beach and Orange counties leading the list. Big northern cities also sent lots of migrants: Cook County, Ill. (home to Chicago); Oakland County, Mich. (near Detroit); and Suffolk County, N.Y. (on Long Island) each sent more than 100 people to Collier County during 2008. 
 
 In second place is Greene County, Ga., with a population of just 15,743 at the Census Bureau’s last estimate. The IRS data show that in 2008, 788 people moved to the county, about 75 miles east of Atlanta. 
 
 Rounding out the top five: Nassau County, Fla., near Jacksonville; Llano County, Texas, 70 miles northwest of Austin; and Walton County, Fla., 80 miles east of Pensacola. 
 
 The dominance of the list by Florida and Texas–the former has eight of the top 20 counties, the latter four– makes sense to Robert Shrum, manager of state affairs at the Tax Foundation in Washington, D.C., since neither state has an income tax. “If you’re a high-income earner, then that, from a tax perspective, is going to be a driving decider if you’re going to move to one of those two states,” Shrum says. 
 
 After accounting for property taxes, Shrum’s analysis shows that Texas has the fourth-lowest personal tax burden in the country, and Florida has the eighth lowest. Shrum also points to eight states that have targeted wealthy households with extra-high tax brackets: California, New Jersey, New York, Maryland, Hawaii, Oregon, Connecticut and Wisconsin. Six of the top 10 counties the rich are fleeing are located in those states. 
 
 Pitkin County, Colo., home to the pricey Aspen ski community, where home listings average more than $3.5 million, saw an exodus of rich people in 2008 as the economy began to contract. The 962 tax filers and dependents who left Pitkin had an average income of $71,473 per capita, while the equivalent figure for those moving to the county was $30,000 lower. Of those leaving Pitkin County, 224 moved to neighboring Garfield County where, according to real estate information service Trulia, homes list for 75% less than those in Pitkin County. IRS data also show movement from the resort area to cities like New York, Chicago and San Francisco. 
 
 Behind the Numbers 
 
 
 
 To find places the rich are moving, Forbes used IRS data on household moves broken down by county and income. We included counties where arriving households are richer than households that didn’t move and departing households are poorer than households that didn’t move. The final ranking orders counties by the difference in per-capita income between incoming households and those that didn’t move. 
 
 Our ranking of places the rich are fleeing essentially reverses these criteria, looking for counties where departing households are wealthier than the population as a whole and where incoming households are poorer. 
 
 In order to find patterns among the wealthy, we restricted the lists to counties where departing or arriving households had per-capita incomes of $35,000 or more. That figure is equivalent to an annual income of $140,000 for a family of four–a very high income for any large subset of the American population (of 3,142 counties with IRS data, only 130 have average incomes above this level). And in order to avoid statistical anomalies, we only included counties with at least 500 people listed as arriving or departing. 
 
 This technique essentially finds new hot spots–places that aren’t necessarily wealthy now but where wealthy people are moving. Some upscale places like Westchester County, N.Y., and Teton County, Wy., don’t make the list because people moving into those counties aren’t as rich as the people who already live there. 
 
 The IRS warns that these counts are only approximations; because they don’t include households that don’t file income tax returns, poor and elderly people are underrepresented. These counts also don’t include returns filed after late-September 2009–a small fraction of total returns that tends to include some very rich people with complex returns who file for extensions. 
 
 Slide Show: Where America’s Rich Are Going (And Leaving) ||||| This year’s list included all U.S. towns and cities with populations of 50,000 to 300,000, for a pool of 823 to start. 
 
 To find the best, we sorted through almost 300,000 demographic data points (which is why we partner with Onboard Informatics to collect it all). For the first cut, we eliminated the 100 places with the lowest predicted job growth, the 200 communities with the most crime, and any place without a strong sense of ethnic diversity (more than 90% of one race). 
 
 Focusing further on pocketbook factors, we hunted for top home values by comparing median property values with median household incomes. We singled out communities with strong local economies and low taxes (property, income, and sales). We also considered accessibility to health care, culture, strong public schools, and sports. 
 
 To correct for geographical biases, we limited the list to no more than four places per state and one per county. 
 
 Reporters spent time in each town, interviewing residents, checking out neighborhoods, and searching for the kinds of intangible factors that aren’t visible in statistics. 
 
 Finally, we arrived at this year’s Best Place to Live. 
 
 NOTES: Rankings derived from 60 data points in the following categories: jobs based on income growth, local unemployment (not seasonally adjusted; county data used when local not available), and projected job growth. Economy based on purchasing power, foreclosure rate, tax burden, and state’s fiscal strength. Housing affordability based on median price-to-income ratio and average property taxes. Education based on test scores, educational interest and attainment, and percentage of kids in public schools. Health based on number of doctors and hospitals in the area and health of residents. Crime based on property and violent crime rates. Arts and leisure based on activities in the town and surrounding area, including movie theaters, museums, and green spaces. Ease of living based on population density, commute times, weather, and other factors. 
 
 Sources: Onboard Informatics, U.S. Bureau of Labor Statistics, FBI, Moody’s, Standard & Poor’s, Kaiser Family Foundation, County Health Rankings, IRS, Tax.org, Tax Foundation, Institute of Taxation and Economic Policy, RealtyTrac, CDC, Infogroup.com, Council for Community and Economic Research, American Alliance of Museums, National Oceanic and Atmospheric Administration, National Association of Realtors, SchoolDigger, FAA, EPA, U.S. Census Bureau, U.S. Postal Service, U.S. Bureau of Economic Analysis, American Community Survey, Federal Housing Finance Agency, National Center for Education Statistics, National Center for Health Statistics, county assessors’ offices, MountainVertical.com, White Book of Ski Areas, National Assembly of State Arts Agencies, Association of Zoos and Aquariums, MCH Strategic Data, Economic Innovation Group, and League of American Orchestras.
– Wealthy Americans are on the move, largely to the low-income-tax havens of the Sunbelt. A new Forbes analysis of IRS data from 2008 shows Collier County, Fla., at the head of the pack, picking up 15,150 new residents with an average income of $76,161—compared to $26,128 for the people moving away. A nifty feature on the Forbes website illustrates the migration and breaks it down by average income, county-to-county. For instance, click on New Orleans (Orleans Parish, La.) and you see graphics showing not just migration in and out but the number of people moving and their average income: to Seattle (King County, Wash.), 56 people, $36,200; from Seattle, 41 people, $25,000. To get the details on migration in and out of the county of your choice—fair warning: it's addictive—click here. To see a slideshow breaking down the most popular destinations, click here.