Between 1880 and 1900, the urban population of the United States rose from 28% to 40%, and reached 50% by 1920, in part due to 9,000,000 European immigrants.
在1880年到1900年间，美国的城市人口比率从28%上升到40%，1920年达到50%，部分是由于欧洲移民的缘故。