On December 7, 1867, engineer Charles Harvey introduced New Yorkers to the first of their elevated rail lines. That same year, the New York Legislature decided not to follow London's example and passed on a subway proposal for Manhattan, so the city was stuck with its frequently malfunctioning elevated lines for another 30 years. Its mass transit went underground only after a blizzard rendered trains inoperable and an epidemic killed 18,000 horses, crippling the city's horse-drawn-coach system.

The epidemic now threatening cities is traffic. Even urban centers with excellent mass transit, like Paris, are choking on cars. In 1959, economist William Vickrey urged members of Congress to charge D.C. motorists during peak hours. They declined, but Vickrey’s congestion-pricing concept eventually won acceptance—in Singapore (the first city to adopt it, in 1975); Oslo (1990); and London (2003)—and validation in Stockholm, where Vickrey was posthumously awarded the Nobel in economic science in 1996.

The New York Legislature has a March deadline to vote on a congestion-pricing plan for Manhattan being pushed by Mayor Michael Bloomberg. With hikes in fuel prices, transit fares, and construction costs, the most likely upshot of any traffic solution will be higher spending all around. Perhaps it's time to take a truly radical step and subsidize walking.