The term "Iron Curtain" refers to the: determination with with the Nazi leaders were condemned.
tension between Arab and Jews over the control of Palestine.
policy of providing aid to help foreign countries fight communism.
division between Soviet controlled countries and the Western world.

Ifound this on google “the existence of agglomeration economies is central to the explanation of how cities increase in size and population, which places the phenomenon on a larger scale. the concentration of economic activity in cities is one reason for their development and growth.” i hope this you for what your looking for.

The american civil war