Pittsburgh is the nation’s oldest city, demographically speaking, with a higher percentage of residents over age 60 than any other metro area, according to an analysis of census data. The Rust Belt city holds the top spot in the gray hairs rating, Forbes reports, reflecting a demographic trend that could have far-reaching effects on local governments.

As America gets grayer — 25 percent of the population is expected to be over age 60 by 2050 — some places are going gray faster than others. Increasingly, the oldest cities are clustered in the old industrial regions of the country. The oldest metropolitan areas have twice as high a concentration of residents over 60 as the youngest, according to Forbes.

The biggest factors are migration and birth rates. Younger people moving toward the South and the West leave behind older residents in traditional industrial hubs. And as the population ages, birth rates drop in many cities. According to the 2010 Census, 10 cities — primarily in the Rust Belt and Northeast — have more elderly than children under age 15.

Aging populations will likely affect local governments. On the upside, a cadre of more secure elderly homeowners helped older cities like Pittsburgh and Boston weather the housing bust relatively better than younger cities like Atlanta. But an elderly population, with less new income and fewer families, could depress tax revenues and consumer demand.

Cities with the highest percentage of elderly residents include:

  • Pittsburgh, 2010 population over age 60, 23.6 percent
  • Tampa-St. Petersburg, over 60 population, 23.5 percent
  • Buffalo, 21.6 percent
  • Miami, 21.3 percent
  • Cleveland, 21.2 percent
  • Hartford, Conn., 20 percent
  • Providence, R.I., 19.9 percent
  • Rochester, N.Y., 19.8 percent
  • Detroit, 18.9 percent
  • St. Louis, 18.9 percent