Is Your City Extreme?

Hottest or coldest, richest or poorest, extreme communities present challenges and opportunities to government and business

By Venessa Wong

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Founded by the Spanish in 1565, St. Augustine, Fla., is the oldest city in the U.S. About two hundred miles to the southwest, Largo, Fla., is the city with the oldest population.

A city near Tampa, Largo saw the percentage of residents aged 85 and older nearly double from 3.4 percent in 1990 to 6.1 percent in 2009, according to U.S. Census Bureau estimates. The U.S. average is 1.8 percent for ages 85 and up.

Most cities in the U.S. are able to maintain a reasonable balance between rich and poor, old and young, healthy and unhealthy. Knowing the characteristics of a city help define its economic health and quality of life. It helps local government plan for what kind of services will be needed and what the tax base will be. Furthermore, it also determines what kind of businesses will flourish there and who will want to move there—or move away.

To find out which were America's Most Extreme Cities, Businessweek.com compiled a list of extremes: hottest and coldest, fattest and fittest, oldest and youngest, richest and poorest, and reviewed data from a number of different sources, including the U.S. Census Bureau's American Community Surveys (ACS), the Bureau of Labor Statistics, the National Climactic Data Center, and others. The findings were adjusted to ensure that the town or city in question had minimum population requirements and were not skewed by the existence of such unusual institutions as prisons. (Click here to see more extreme places, based on ACS estimates.)

What's Hot, What's Not

How does a city go to extremes? In some cases, the answer is purely geographical. Lake Havasu City, Ariz., is the city with the hottest July temperatures. (Death Valley has higher temperatures, but it is not a city.) To use another example, Williams County, N.D., has the nation's strongest job market, thanks to an economy based on agriculture and oil.

In many other cases, though, the answer is more selective. "We're a country where segregation by economics, race, and ethnicity is part of the landscape," says William Frey, a demographer at the Brookings Institution. In some cases, demographic extremes can result from migration—or lack of migration, he adds, as people tend to want to live with people similar to them.

Supporting communities with huge demographic imbalances can be difficult. As regulators, businesses, and community leaders prepare to meet the demands of a U.S. population that is growing, aging, and struggling to find work, places with extreme demographic disparities will have to address their own outsize needs.

Small Towns, Big Families

One place that exceeds many demographic averages: the village of Kiryas Joel, a Satmar Hasidic community about 50 miles from Manhattan in New York's Orange County, where more than half the residents are younger than 15, a larger portion than any community nationwide with a population of 20,000 or more, according to Census Bureau estimates. (Hildale, Utah, has the highest proportion of children but has a population of only around 1,500.) By contrast, about one-fifth of the U.S. population is under age 15.

As birth control is not practiced and large families are customary, families in Kiryas Joel typically have eight to 10 children, and each year 150 new households are created, according to Ari Felberman, public relations director for the village. Only about one in three Kiryas Joel residents are aged 18 and older, and the village has a median age of 11.9, well below the national median of 36.8, estimates the U.S. Census Bureau.