In U.S. politics, "seniors' issues" usually means Medicare and Social Security and how much to spend on them. That needs to change, as a new report from the Organization for Economic Cooperation and Development illustrates: The pressure of demographics will turn plenty of more mundane things into seniors' issues. For a glimpse into that future, take a look in Philadelphia's garages.

The city is being squeezed by an aging population, poverty and housing costs. One in 7 Philadelphians are already 65 and older, a number that is projected to grow 24 percent by 2020. Most want to stay in their own homes. Many are poor. And as in many U.S. cities, money for social services is tight: Philadelphia's budget fell 12 percent from 2013 to 2014 alone.

So in 2011, the city council adopted zoning changes that make it easier to build "accessory dwelling units" -- such as garage, basement or backyard apartments -- designed for the elderly to move into while they rent out their homes to make money or their families move in as caregivers.

Putting granny in the garage might not seem like loving elder care, but the OECD's report shows that cities need to try new policies, and fast. From 2001 to 2011, the number of people 65 or older living in developed-country cities jumped 24 percent -- three times the speed of growth for those cities as a whole. By 2050, 1 in 4 people will be 65 or older, with the fastest growth among those 80 and up.

That means more than just finding new places for seniors to live. The report looks at cities in North America, Europe and Japan that have already started grappling with the needs of their aging populations:

-- Cologne, Germany, started a program that lets students move in with seniors for free, in return for acting as caregivers. The city is also encouraging small shops to relocate to residential areas, to make shopping easier for seniors who can't use cars.

-- 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.