[giantg2]

They aren't wrong, and neither are you. Population growth was large in the cities due to immigration. And if you had many children on a farm, you couldn't divide the land for the next generation and still be profitable, so they had to move to cities. What happened from the 50s-80s were small farms being given up because they weren't economical.

The machinery during the 50s-60s eliminated a lot of agricultural jobs, and drive down prices. Not just for farmers, but also in processing agricultural products.