Cities

In the United States a frequent source for cycling-infrastructure design is the American Association of State Highway and Transportation Officials’ Guide for the Development of Bicycle Facilities. In its current form, the guide favors one-way bike lanes separated from vehicular traffic by painted lines; cycle paths at sidewalk level are discouraged and physically separated two-way paths, known as cycle tracks, are not mentioned.

U.S. streets have been filled with traffic since the country’s founding — first with wagons and livestock and now with more than 250 million autos and trucks. Building more and wider roads can reduce congestion, but the benefits are generally temporary: Vehicles soon fill new lanes, and the cycle starts all over again. The massive highway boom after World War II did speed cross-country travel, but it also added suburban congestion to the list of pressing national problems.