The growth of cheap transportation and electricity led to the decentralization of industries and warehouses. Industrial employment began to develop in the suburbs, in the 1960s half of the jobs took place here. Retail has been decentralized to the suburbs, for example the County Club Plaza has been decentralized to Kansas City. Shops and retail outlets, especially huge enclosed malls, have become catalysts for development. Traditional suburbs have developed in such a way that they are defined as a form of decentralized city, with Joel Gatreau calling it a fringe city – an area developed and shaped by transport. Examples of edge cities include California, Virginia, Silicon, and Tyson's Corner. The Depression and World War II caused a slowdown in the growth rate of suburbanization, including family formation and home construction. The end of the Depression and World War II led to increased pent-up demand and the baby boom which led to prolonged periods of prosperity and growth; suburbanization became both the hallmark and outcome of that period. Levviton's development prototypes and development plans played an important role in the production of the homes, with 150 homes produced in one week. The completion of the project, developed by Levvit - the mass home builders - resulted in the completion of 17,000 homes, reduced below market value and thus allowing for a greater population of the United States