Answer:
By 1900, the population in New York City, Chicago, and Philadelphia had each grown to exceed one million people.
Step-by-step explanation:
Due to the positive impact of industrialization, the population of urban centers in America increased greatly. In 1870, only two cities in America had populations that were more than half a million; by 1900, the number of cities that had populations higher than half a million, increased to six. The population in each of three cities (out of the six)—Chicago, New York, and Philadelphia—had grown to exceed one million people.