The population is aging rapidly as the baby boomers begin to enter the retirement years. The median age of U.S. residents grew from 35.3 years in 2000 to 37.2 years in 2010, according to recently released Census Bureau data. In some communities, more than half of the population is over age 40.
"The aging of the baby boom population is contributing to the increase in the median age," says Lindsay Howden, a Census Bureau statistician and co-author of the report. "Other contributing factors are improvements in mortality and a stable birth rate."
[In Pictures: 10 Places with the Oldest Population.]
Those on the verge of retirement make up the country's fastest-growing group of people. There are now 81.5 million Americans between ages 45 and 64, up 32 percent since 2000. The proportion of people age 65 and older climbed 15 percent to 40.3 million. By contrast, the number of people under age 18 has grown just 3 percent since the beginning of the decade, to 74.2 million.
All states have experienced an increase in median age since 2000. There are now seven states where the median age is above 40: Maine, Vermont, West Virginia, New Hampshire, Florida, Connecticut, and Pennsylvania. In earlier decades, all states had a median age below 40. The states with the largest increase in median age over the past 10 years were Maine (up 4.1 years), New Hampshire (up 4 years), and Vermont (up 3.8 years). Utah is the only state that still has a median age under 30. The regions with the oldest median age are the Northeast (39.2 years) and the Midwest (37.7 years). Residents of the South (37 years) and West (35.6 years) are somewhat younger.
The variations in median age are mostly due to young people moving to new places, according to William Frey, a demographer and Brookings Institution senior fellow. But in some cases, the median age growth was driven by older people relocating to communities that cater to seniors. "Florida is a place where older people have moved to," says Frey. "The other places are aging because the young people are moving away."
The aging population is changing the ratio of dependents to current workers. Only 13 percent of the population is currently age 65 or older and 24 percent of the population is under age 18. However, the ratio of dependent children under age 18 to the working-age population has declined by 3.3 percent since 2000, while the proportion of old-age dependents has increased slightly by 0.6 percent. More than a quarter of the population (26.4 percent) is currently between ages 45 and 64 and heading toward the retirement years, which is likely to cause the number of old-age dependents to further rise. Alaska has the lowest old-age dependency ratio and Florida has the most old-age dependents relative to current workers.
Scottsdale, Ariz., has the oldest citizens of any city with a population of 100,000 or more. The median age of 45.4 years is eight years higher than the national median age. There are also five cities in Florida and two in California that are among the cities with the oldest citizens. "Florida has one of the lowest state and local tax rates of any state, and there is no income tax in Florida," says Stanley Smith, a University of Florida economics professor who studies the demography of Florida. "For retirees, there are also a lot of similar people in the same types of circumstances that you are."
Interestingly, Florida also has two places among the 10 cities with the lowest median age: Gainesville (24.9 years) and Tallahassee (26.1 years). "Florida has characteristics that can attract people at both ends of the age spectrum," says Howden. "It has planned retirement communities for people at older ages and things like prominent universities that attract people at younger ages." Cities with the youngest median ages tend to have a major college or military base, while places with the oldest citizens often have retirement communities, pleasant weather, and other amenities that appeal to seniors.
Here are the 10 cities with the oldest median ages:
1. Scottsdale, Ariz.; 45.4 years
2. Clearwater, Fla.; 43.8 years
3. Cape Coral, Fla.; 42.4 years
4. Fort Lauderdale, Fla.; 42.2 years
5. Hialeah, Fla.; 42.2 years
6. St. Petersburg, Fla.; 41.6 years.
7. Thousand Oaks, Calif.; 41.5 years
8. Honolulu, Hawaii; 41.3 years
9. Torrance, Calif.; 41.3 years
10. Centennial, Colo.; 41.1 years
Source: Census Bureau, 2010.