What happened to the population of cities in the period between the Civil War and the 1920s?

The population of cities in the period between the Civil War and the 1920s dramatically increased. During this period there were large waves of European immigrants from Ireland, Germany, and other regions who came to the US seeking a better life and often took up residence in American cities. In addition there was increased migration of African Americans into cities during this period following the ending of slavery. Overall there was a dramatic increase in urban populations across the US during this time period.