问答题 During the 20th century, as the population of the United States became increasingly urban, new Thanksgiving traditions emerged that catered to city dwellers. The day after Thanksgiving gradually became known as the first day of the Christmas shopping season. To attract customers, large retailers such as Macy’s in New York City and Gimbel’s in Philadelphia, Pennsylvania, began to sponsor lavish parades. By 1934 the Macy’s parade, featuring richly decorated floats and gigantic balloons, attracted more than one million spectators annually.