Though they're individually tiny, parking spots quietly play a dominant role in shaping urban landscapes. Most US cities dedicate at least 25% of their developable land to them. Some, even more. That land usage doesn't only determine the way a city looks. It also means covering large swathes of urban areas in heat-absorbing asphalt, which contributes to making summers hotter and heightens the risk of flooding since it prevents drainage during storms and heavy rainfall.