one with a much lower down payment. At the same time, African Americans were rapidly moving north and west for better jobs and educational opportunities than were available to them in the segregated South. Their arrival in Northern and Western cities en masse, in addition to being followed by race riots in several large cities such as Philadelphia, Los Angeles, Detroit, Chicago, and Washington, D.C., further stimulated white suburban migration. The growth of the suburbs was facilitated by the development of zoning laws, redlining and numerous innovations in transport. The policy of redlining and other discriminatory measures built into federal housing policy furthered the racial segregation of postwar America for example by refusing to insure mortgages in and near African-American neighborhoods. The government's efforts were primarily designed to provide housing to white, middle-class or lower-middle-class families. African-Americans and other people of color largely remained concentrated within decaying cores of urban poverty creating a phenomenon known as white flight. After World War II, availability of FHA loans stimulated a housing boom in American suburbs. In the older cities of the northeast U.S., streetcar suburbs originally developed along train or trolley lines that could shuttle workers into and out of city centers where the jobs were located. This practice gave rise to the term "bedroom community", meaning that most daytime business activity took place in the city, with the working population leaving the city at night for the purpose of going home to sleep. Economic growth in the United States encouraged the suburbanization of American cities that required massive investments for the new infrastructure and homes. Consumer patterns were also shifting at this time, as purchasing power was becoming stronger and more accessible to a wider range of families. Suburban houses also brought about needs for products that were not needed in urban neighborhoods, such as lawnmowers and automobiles. During this time commercial shopping malls were being developed near suburbs to satisfy consumers' needs and their car–dependent lifestyle. Zoning laws also contributed to the location of residential areas outside of the city center by creating wide areas or "zones" where only residential buildings were permitted. These suburban residences are built on larger lots of land than in the central city. For example, the lot size for a residence in Chicago is usually deep, while the width can vary from wide for a row house to wide for a large stand–alone house. In