It's definitely a thing in the US. 64% of the population lived in urban areas in 1950 compared to 81% in 2010.
https://en.wikipedia.org/wiki/Urbanization_in_the_United_Sta...
https://en.wikipedia.org/wiki/Urbanization_in_the_United_Sta...
The massive change in urbanisation is happening in developing countries. In developed countries it happened earlier and is not really a thing anymore.