Can you imagine if everything you needed in your everyday life was just a walk or bike ride away? That’s the goal of the 15-minute city, a new name for an old idea. Reducing the need for cars cuts emissions and gets autos off of the roads, which is a boon for safety, air quality and the climate. But, as is often the case, good ideas become a lot more difficult when you have to implement them in real places, with real people, who don’t always share the enthusiasm for the idea. What will it take to make compact, walkable cities a reality in the U.S., where the car is king?