W.E.B. Du Bois added to his words by arguing that the second main component of the American dream (property) also reemerged in the late 1940s. New means of construction led to a rapid expansion in the housing industry. By the 1950s approximately two million new homes were being built each year for the forty million Americans who fled the urban areas for the new suburbs. The expansion of the federal highway system made it possible for some ninety percent of workers to drive to their places of employment. Yet the growth of the suburbs further segregated society as the white middle class left urban centers. The loss of this purchasing power and tax base led to a lessening of services and commerce. The overall urban decline in the United States of the late 1960s and 1970s continued to accentuate the difference between the prosperous groups and the growing urban poor.