When it comes to moving people around in healthy ways, New York City already has a leg up on most cities and towns around the country.

The city has sidewalks in all five boroughs; food stores and other shops are within walking distance of where most people live. It is served nearly everywhere by extensive, inexpensive and largely dependable public transportation. City children have long been able to walk, skate or scoot to school, though these days fewer attend schools in the neighborhood.

Because so many New Yorkers use their feet to get them from place to place, they weigh on average six or seven pounds less than those who live in suburban America, said Dr. Richard J. Jackson, professor of environmental health sciences at the University of California, Los Angeles, and moderator of a public television series called “Designing Healthy Communities.”

Despite a rising tide of pedestrians and cyclists, the number of traffic-related deaths on city streets fell last year to the lowest level in a century, declining 40 percent since 2001. Although cyclist deaths did rise in 2011 for the second year in a row, the per capita death rate for cyclists has dropped.

Developing a Master Plan

Janette Sadik-Khan, the city’s transportation commissioner, attributes these improvements to an ambitious plan-in-progress to re-engineer city streets. Recent years have seen a plethora of projects to improve pedestrian and cycling safety, including pedestrian plazas, well-marked crosswalks, bike lanes (both segregated and shared with vehicles) and timed traffic signals that enable pedestrians to better judge their ability to cross streets safely.

The timed signals were late in coming to New York, which now has 1,100 so-called countdown signals at pedestrian crossings. I first encountered these signals two decades ago in Seattle. I was delighted to find one the other day when I crossed Park Avenue at East 64th Street with a friend in her 80s who recently had back surgery and walked slowly with a cane.

The city is also enhancing enforcement of traffic laws, with more summonses for drivers who ignore stop signs, sail through red lights, and talk or text on a handheld device while driving. But as Ms. Sadik-Khan acknowledges, this is only the beginning; a lot more must be done to make the city streets safer for people who wish to navigate them under their own steam.

As James F. Sallis of San Diego State University and co-authors wrote in “Making Healthy Places,” a compilation of academic reports on urban design published last year by Island Press, “People are more likely to choose to walk for transportation and for recreation when there is good pedestrian infrastructure.”

Just 1 percent of federal transportation funds are spent on pedestrian and bicycle facilities, David A. Sleet and co-authors at the Centers for Disease Control and Prevention noted in the book.

Not coincidentally, pedestrian deaths in the United States are three times as high per capita as in Germany and five times as high as in the Netherlands. Safer road designs in these countries slow motor vehicles and separate them from pedestrians and cyclists.

Enacting similar changes to encourage physical activity in suburban America is no small task. In The Natomas Buzz, a Web site about a neighborhood in Sacramento, Brandy Tuzon Boyd, a reporter, recently described the promising plans and frustrations of trying to improve walking and biking access and safety in Natomas, a bedroom community that now covers 22 square miles.

Yes, there is a new and well-used bike and pedestrian bridge that connects community trails on one side of a freeway to trails on the other side. There is a program to teach students how to travel safely to school on foot and by bicycle. Crossing guards have been posted. Helmets were provided for cycling students who couldn’t afford them.

Awareness among students and parents of the value of physical activity is decidedly up. But that is not enough: Cars still often fail to heed stop signs and red lights, and one of the region’s most popular cycling routes is still too narrow and dangerous.

In the past decade, there were more accidents reported between cars and cyclists in Natomas than between cars and pedestrians.

Still, a master plan to improve walking conditions and calm traffic is in place, with speed humps, marked crosswalks, pedestrian islands and other measures intended to enhance the physical activity and health of residents, young and old.

Physical Benefits

As more people like those in Natomas rely on themselves instead of fuel-driven vehicles to get from place to place, experts expect a decline in health problems known to be aggravated by air pollution, stress and inactivity: asthma and other respiratory diseases, heart disease, high blood pressure, Type 2 diabetes, depression and even some cancers.

But as Margaret Schneider, an associate researcher at the University of California, Irvine, wrote in “Making Healthy Places,” “As important as the built environment is, it is far from being the only determinant of health. Even well-lit, cheerful staircases; broad, attractive sidewalks; and safe, well-constructed bicycle paths may not seduce people into forgoing the elevator, walking to work, and cycling on errands.”

She added: “Even when walkable neighborhoods are available, people may still choose to live in far-flung suburbs, reducing their opportunities for routine physical activity.” Accompanying her report is a picture of a dog walking in a park on a leash held by a woman in a car.

Still, there is evidence that if you build it, they will come. Twenty-three percent of the users of two new community trails established in Morgantown, W.Va., were “new exercisers” who were more dependent on the trails for physical activity than people using them who were already habitually active, according to a report by Paul M. Gordon and colleagues at the Centers for Disease Control and Prevention.

Such trails are also likely to be cost-effective. Of four trails established in Lincoln, Neb., the average cost for a person who became physically active as a result was $98, certainly much less than what even a minor health problem related to a sedentary lifestyle would cost.