Urban planners have long considered public transportation the best remedy for traffic congestion, but many of the nation’s largest mass-transit systems aren’t up to the task.

They lack the money to keep up with basic maintenance, let alone modernize and expand to attract more riders and take pressure off the highways connecting growing cities and suburbs.

In Tucson, a $2.4 million cut to the city’s transit system is expected to impact 1 out of every 4 families.

Fewer stops and longer waits along nine routes will only add to average 41-minute commute for Sun Tran riders, data compiled by The Associated Press show

That figure is only slightly below the national average, where riders spend 49 minutes riding in each direction on some form of mass transit.

Those driving into work fare only slightly better, spending an average of 25 minutes on Tucson’s pothole-filled roads, compared to the national average of roughly 26 minutes.

Tucson’s problems pale in comparison to Boston, where the oldest American subway system began operating in 1897. During a winter of record-setting snow, the Massachusetts Bay Transportation Authority was often paralyzed, its antiquated equipment overwhelmed by the elements.

By late February, “the T,” as locals call it, had less than half of its fleet available. Service was not fully restored until the end of March.

At the height of one storm, police helped ferry doctors and nurses to hospitals so emergency rooms could stay open. Schools closed. Businesses suffered, along with countless workers, especially hourly-wage employees who couldn’t get to their jobs.

What happened in Boston over the winter was extreme, but transportation experts and policymakers say it’s emblematic of chronic underinvestment in urban transit systems at a time when demand is growing in many areas.

Under ideal circumstances, public transit systems would extend their reach, offering more trains, buses and ferries, longer hours and new routes serving a wider geographical area. Newer systems in cities such as Los Angeles and Denver have plans to do just that.

But the so-called “legacy” systems serving Boston, New York, Philadelphia, Chicago, San Francisco and Washington face a dilemma: Should they use limit

ed money to shore up their creaky infrastructure or stretch it to expand service as populations grow?

In Boston, some critics of the T say the agency dug itself in a hole by expanding even as its core infrastructure deteriorated, leaving the nation’s fifth-largest transit system heavily in debt.

Moreover, a 2014 survey of millennials in 10 large U.S. cities found that 3 in 4 young adults envision living in a place where they will not need a vehicle to get around. Yet many also rate their own regions as “fair” or “poor” when it comes to public transportation options, says the study by The Rockefeller Foundation and Transportation for America.

The Federal Transit Administration estimates the cumulative national cost of fixing or replacing transit assets in disrepair or operating beyond their useful life at $87.7 billion.

Star reporter Joe Ferguson contributed to this story. Contact him at 573-4197 or jferguson@tucson.com. On Twitter: @JoeFerguson