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The United States has been an urban society for about a century.Today，more than 80％ of the population lives in urban areas.U.S.cities are cultural centers with a rich variety of museums，art galleries，theaters，concert halls，and a diverse range of shops and restaurants.They are also centers of commerce and finance，as major corporations，banks and other business institutions are usually located in the cities.

However，since the mid⁃twentieth century，many people have moved away from the crowded city centers to the suburbs.Many Americans prefer to live individual private houses that are separated from their neighbors，and this type of home is difficult to obtain in the cities.The rapid development of highways and automobile ownership after World WarⅡmade it possible for people to commute between suburban homes and their workplaces in the cities，which helped to fuel the trend towards suburbanization.Suburbs also offered the promise of an escape from the problems of big cities such as crime and pollution.Cheaper and more sparsely populated land in the outlying suburban areas helped make it affordable for middle class people to buy individual private houses.At present，two⁃thirds of urban Americans live in houses in the suburbs.However，about one⁃third of the urban population reside in the inner cities，especially blacks and new immigrants，many of whom live in huge apartment complexes or government subsidized housing in poorer neighborhoods.

Map of the Seal of the United States

The preference for living in suburbs has led to the emergence of large shopping centers outside the city.Although urban areas have an abundance of stores，many consumers shop outside the city at shopping malls，huge“big⁃box”superstores such as Wal⁃Mart and Target，large wholesale stores like Costco and Sam’s Club，and factory outlets where manufacturers sell their products direct to consumers at a large discount.