Aging forces cities to rethink everything

– In Helsinki, an emphasis on keeping people in their homes for as long as possible, combined with an expected shortage of trained home-care staff, led to the development of floor-sensor systems that let nurses monitor seniors remotely. The city is also trying to get more elderly residents comfortable using computers for their everyday needs.

– In Lisbon, an explosion in the share of seniors, from 9 percent in 1960 to 24 percent in 2011, has turned the city's picturesque network of narrow and uneven sidewalks into a trap. So Lisbon set a minimum width of five feet for its sidewalks, and is trying a public-awareness campaign to get drivers and other pedestrians to watch out for seniors on foot.

– In Calgary, the tight job market driven by the oil boom has pushed the city to look for ways to keep more seniors employed, by retaining retired workers on short-term projects. And the share of those 65 and over is projected to double by 2042, so the city is also trying to rein in sprawl and increase the availability of transit, with an eye to making it easier for the elderly to reach social services.

– In Brno, Czech Republic, where 19 percent of residents are 65 or older, a wave of crime directed at seniors has led city police to train some as "crime prevention assistants." The goal is community policing for seniors, by seniors. It's also encouraging the elderly to move into shared apartments, with separate bedrooms but common kitchens or bathrooms.

– In Manchester, England, an aging population has been made worse by high rates of chronic disease, which usually starts before somebody hits 65. So the city has started thinking of its seniors' policy in terms of people 50 or older, given their high unemployment and tendency to have medical conditions.

– Seniors' policy doesn't always focus just on seniors. In Yokohama, Japan, where 22 percent of residents are 65 or older, the working-age population is falling, shrinking the tax base. The city is trying to attract younger families, including cutting the number of kids on child-care waitlists to zero.

The OECD report shows that most developed cities face a variation of the same basic challenges: increasing the supply of affordable and accessible housing, making it easier for the elderly to get around safely and stay active, and finding ways to provide social services and other care for less money.

For all the association between cities and young people, the advantages of urban living appear even more relevant for the elderly. Close-quarter living isn't everyone's preferred lifestyle, especially in the U.S. But the hallmarks of aging — smaller households, more difficulty driving, the need for social interaction and proximity to services — all point to the benefits of cities. Urban issues are becoming seniors' issues.