How has urbanization affected population distribution in the United States?

Urbanization caused many people to cluster into large cities. When a city was forming, many jobs began to open. People would leave their unstable farming, trading, fishing etc ... jobs in the rural areas for a more secure factory, office, business job opportunity in the city. This means that the population is distributed unevenly across the US, with the majority of people living in urban areas.

Populations of metropolitan areas have increased.