How cars killed the dream of the moving sidewalk

Despite making its debut almost a century and a half ago at the 1893 Chicago World's Fair, the moving sidewalk hasn't made much headway in the modern world outside of airports and theme parks. 

An article by Bill Gourgey in Popular Science traces the history of the moving sidewalk concept and its various applications since it was first invented. One of its early champions, Alfred Speer, first proposed an elevated moving sidewalk on New York City's Broadway as a solution to congestion. "Today, a confluence of factors, including aging populations in need of mobility assistance, the spread of 'complete streets' to establish more car-free zones, and the climate-driven pressure to rethink mass transit, may be creating favorable conditions for new versions of Speer’s vision."

Cities and companies have made various attempts at using moving sidewalks with varied degrees of success. Ultimately, they have found their niche in airports, theme parks, and other contained places with limited destinations. Today, Hong Kong's Central-Mid-Levels Escalator, which connects hillside neighborhoods with the city center, is the world's longest covered escalator system.