City planners and preservationists say a key to keeping downtown Charleston livable, as the population grows, is finding ways for people to get where they need to go without using a car.

A Census Bureau report this week highlights the size of that challenge.

In towns and cities across the United States, more people are biking to work, but they still account for less than 1 percent of all commuters. In Charleston, an estimated 2.2 percent commute by bike.

Census surveys also found that the percentage of Americans who walk to work has fallen by 50 percent since 1980, to 2.8 percent.

Count up the walkers, bikers, commuters who use mass transit, and those who work at home, and the nation is left with more than 86 percent of people across the U.S. getting to work in a car, truck or van.

The South as a region has the lowest percentages of people who walk or bike to work, and that can't all be blamed upon hot summer weather. In frigid-winter Ithaca, N.Y., more than 42 percent walk, while in steamy Key West, Fla., more than 18 percent bike.

In South Carolina, as in other parts of the nation, cities with large college populations had higher numbers of commuting walkers and bikers. Those commuters likely included lots of college students, but they would have been students who were commuting to jobs, because only those with jobs were surveyed for the census report.

Columbia ranked sixth among medium-sized cities for commuters who walk, with 11.3 percent. In Charleston, the estimated 2.2 percent who commute by bike placed the city 12th among medium-sized cities.

Reach David Slade at 937-5552