America's first enclosed mall was built in 1956, and the nation hasn't looked back. About 1,500 malls were built in the U.S. from 1956 through 2005, providing hubs for social gathering and shopping throughout America's booming suburbs. By 1975, malls accounted for 50% of U.S. retail dollars spent, representing an impressive 13% of GDP. So much property was developed that by 2017 America had an estimated 26 square feet of retail for every person in the country, compared with less than 3 square feet per capita in Europe, according to Time. But now, in the age of Amazon, many areas of brick-and-mortar retail, including malls, are being forced to right-size their footprints.