In 1940, we were coming out of a great depression. The US was still highly agriculture. A huge amount of it had to do with the recovery of the economy and the mobility from the world to the urban areas. We came up on the farm. So agriculture became very productive and you left behind a group of people who were on average making much more income.
Economist and Nobel Laureate James Heckman of the University of Chicago talks about inequality and economic mobility with EconTalk host Russ Roberts. Drawing on research on inequality in Denmark with Rasmus Landerso, Heckman argues that despite the efforts of the Danish welfare state to provide equal access to education, there is little difference in economic mobility between the United States and Denmark. The conversation includes a general discussion of economic mobility in the United States along with a critique of Chetty and others' work on the power of neighborhood to determine one's economic destiny.