“The middle-class society I grew up in didn’t evolve gradually or automatically. It was created, in a remarkably short period of time, by FDR and the New Deal. As the chart shows, income inequality declined drastically from the late 1930s to the mid 1940s, with the rich losing ground while working Americans saw unprecedented gains. Economic historians call what happened the Great Compression, and it’s a seminal episode in American history.”
How it happened is even more remarkable - during a period of scarcity, inflation, recycling, rationing, regulation and high government spending had the result of marking the only major decrease in inequality in U.S. history, with people making more money and saving much more. What’s more, trade was severely disrupted (to say the least) as supply lines to countries who supplied raw materials as well as manufactured goods were cut off, and there was no free movement of people across borders.
The result was the creation of the middle class - and it happened in Canada, too.
https://www.presidency.ucsb.edu/documents/message-congress-curbing-monopolies
https://www.mcnallyrobinson.com/9780143117636/ellen-ruppel-shell/cheap?blnBKM=1