According to a recent Brookings Institution analysis of 2010 Census Bureau data, the age-65-and-older population increased by 15 percent between 2000 and 2010. However, there are many major U.S. cities that are aging at a much faster rate than that.  

"Most of the country is increasing its over-age-45 population simply because people are aging in place," says William Frey, a Brookings Institution senior fellow and author of the report in an article on US News.

There are some people that move to designated retirement communities once they leave their jobs, but most people don't.

"There is some movement among the retired population, but it's not that huge and people who move typically move locally," says Frey. "Florida is the outlier. In the rest of these places the migration is occurring among people under age 45."

Most people tend to retire near the place they spent their career.

The following is a list of 10 fast-growing retirement spots:

1. Raleigh-Cary, N.C.: 60 percent

2. Austin-Round Rock, Texas: 53 percent

3. Las Vegas-Paradise, Nev.: 50 percent

4. Boise City-Nampa, Idaho: 46 percent

5. Atlanta-Sandy Springs-Marietta, Ga.: 44 percent

6. Provo-Orem, Utah: 42 percent

7. Colorado Springs, Colo.: 40 percent

8. Houston-Sugar Land-Baytown, Texas: 39 percent

9. Dallas-Fort Worth-Arlington, Texas: 38 percent

10. Charlotte-Gastonia-Concord, N.C.-S.C.: 36 percent

Source: Brookings Institution analysis of Census Bureau, 2010