For a city to be aging-friendly, its residents need affordable and safe housing, opportunities for staying engaged in activities that matter to them and access to health care and other services. An aging-friendly city also offers opportunities for people to work, for pay or not. By 2050, the population over age 65 is projected to reach 83.7 million, almost double 2012’s roughly 43.1 million.

Here are examples of some age-friendly cities:

Portland, Ore. A strong transportation system is one asset of Portland, which was one of the original nine members of the World Health Organization’s Global Network of Age-Friendly Cities and Communities.

New York City The city, during the administration of Mayor Michael R. Bloomberg, increased the number of benches at city bus stops, opened senior hours at city pools and improved street crossings. The city has also created a searchable database for adult learning courses.

Iowa City, Iowa Home to the University of Iowa, it was named the best small city for successful aging by the Milken Institute in 2014. College towns have lively entertainment, sports and, often, ample jobs for people not yet ready to stop working. Iowa City offers low health care costs and financial incentives for the construction of affordable housing. The city provides door-to-door transit service for those unable to use the bus system.

Los Angeles Mayor Eric Garcetti and Hilda L. Solis, chairwoman of the Los Angeles County Board of Supervisors and a former secretary of labor under President Obama, recently unveiled Purposeful Aging Los Angeles, a five-year plan incorporating civic engagement of older adults, philanthropic organizations, community organizations, businesses and educational institutions. From 2010 to 2030, older adults in the Los Angeles region are expected to nearly double to 2.1 million.

Madison, Wis. It has been praised for its employment opportunities and low poverty rate for older adults, a low crime rate, quality health care, intellectual engagement at the University of Wisconsin, an abundance of recreational and fitness activities, and low rates of smoking, falls and diabetes among older people. Housing is considered expensive, however.

Cleveland and Minneapolis these cities get attention because of their world-renowned medical centers. No surprise, cities with heralded medical centers make the Milken Institute list for people 80 and older.

Sausalito, Calif. The city has been singled out for Call a Ride Sausalito Seniors (Carss), a program that provides free rides for seniors 60 and older.

And More Omaha, Boston, Sioux Falls, S.D., and Columbia, Mo., have also made the Milken Institute’s list for health care and high employment among older adults.