Where to retire? It's an age-old question that for many people centers on two big variables: housing costs and taxes.

They should add a third criterion to their list: the percentage of people collecting pensions.

Most people tend to retire close to home, according to an analysis of U.S. Census data by Cheryl Russell, a demographer and editorial director of New Strategist Publications. Those who move farther away fall into two groups: the frail elderly, who want be closer to their children, and, as Ms. Russell calls them, the "energetic affluent."

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For those looking make a long-distance move, the websites Zillow, Trulia and Realtor.com provide listings, historical sales prices, mortgage rates, property taxes and foreclosure rates, among other information.

Zillow, for example, shows trends within states and metropolitan areas over one, five and 10 years, the percentage of homes sold for gain or loss, and the percentage that increased or decreased in value. Trulia includes data on crime rates and schools, and Google Earth lets you peek at the property.

Taxes are more complicated. States vary considerably, with different rules for different kinds of income.

Tennessee, for example, doesn't tax wages, Social Security benefits, or pension and IRA distributions. But the state sales tax is high (7% for tangible property, for example), and it taxes interest and dividends at 6%. Estate and inheritance taxes range from 5.5% to 9.5%.

Florida has fewer variables. It has no state income tax of any kind, no inheritance tax and limited estate taxes. Property taxes have a number of homestead exemptions. The state sales tax is 6%, though some counties have a sales tax that can bring the combined rate to 9.5%.

Each state's Department of Revenue or Taxation has a website with a breakdown; the Retirement Living Information Center offers a detailed state-by-state breakdown on its website.

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But beware: Low taxes alone aren't enough. Areas with low taxes may have crumbling infrastructure, high unemployment and deficit spending. They may have closed their parks and laid off half their police force. And taxes may rise, especially in areas where public pensions are seriously underfunded.

Illinois, for example, doesn't tax income from pensions, retirement plans and most Social Security benefits. But this year, in the wake of the budget crisis, the legislature temporarily raised taxes on income, including investment income, from 3% to 5%.

For state-by-state research and analysis on policy developments on a range of issues, including the economy, spending, health and retirement, check out the Pew Charitable Trust's Pew Center on the States.

Pension obligations aside, one factor that is often overlooked is the percentage of households with pension income. States with many pensioners have greater financial stability, according to an upcoming study by Frank Porell, an economist at the University of Massachusetts Boston.

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"These households are better off, spend more money, pay more taxes and rely less on government support," says Mr. Porell. Households with pension income range from 54% of households in Minnesota to 24% in South Dakota, including households with retired public employees.

Teachers, firefighters and other public employees tend to retire in the area where they worked, and their pensions get pumped back into the local economy. It also generates local taxes—$1 billion in Illinois, for example—that help offset the impact of underfunded pensions.

The National Institute on Retirement Security, a nonprofit research group, analyzed the economic impact of state and local pensions in all 50 states. According to its recent report, in Florida, where the average benefit is $20,000, each $1 dollar paid in state and local pensions produced $4.47 in economic activity.

Diane Oakley, the director of the institute, says the impact of pension expenditures helps keep property values stable, and might be especially vital to small or rural communities.