An edge city is an American term for a concentration of business, shopping, and entertainment outside a traditional downtown (or central business district) in what had previously been a residential or rural area. The term was popularized in the 1991 book Edge City: Life on the New Frontier by Joel Garreau, who established its current meaning while working as a reporter for the Washington Post. Garreau argues that the edge city has become the standard form of urban growth worldwide, representing a 20th-century urban form unlike that of the 19th-century central downtown. Other terms for the areas include suburban activity centers, megacenters, and suburban business districts.