Associate Professor of Urban Planning Adam Millard-Ball spoke to Bloomberg CityLab about his research on the land value of streets in the United States. Millard-Ball calculated the widths, land areas and land value of streets in 20 different counties in the U.S., and he found that streets averaged 55 feet wide, even in residential areas with low traffic. Streets are much wider in the United States than in other parts of the world. In the counties he surveyed, Millard-Ball found that streets took up 18% of the total land area. He said cities could use some of the land currently allocated to streets for bike lanes, transit, green spaces or housing. He also noted that decreasing standard street sizes could help reduce housing development costs. “People are already using streets for housing, just not in a sanctioned way,” he said. “Why do we rule out 20% of a city’s land and declare it off limits for that?”