The percentage of Americans employed as farmers in the US far exceeded that of trucker drivers. Yes there was disruption, but those people didn't permanently go on to be the underclass unemployed of society. They and their descendants went on to more fruitful activities. The thing is, at the time, you couldn't imagine what those activities would be.
Oh, you mean all the farmers and factory workers that made up the Midwest, which are now overwhelmingly trump supporters, largely because of the destruction of all economic opportunity in their region?
Sorry, I should have reserved my comment for a day when I am not recovering from a sinus infection :) Farming, in the midwest at least, was a dying but still widely practiced profession up into the early 80's. This also includes meat farming. The farm consolidation really got into the swing of things in the mid 80's. Add in the decimation of the auto and steel (and supporting industries) and you see a period from 1960 - 1990 that had an unprecedented level of people forced out of work due to automation and lost jobs.
The Trump comment was tossed in because it's been easy to forget about this stuff as a coastal living millenial, and the recent Trump phenomenon has brought it back to the forefront.
[0] http://www.usda.gov/factbook/art/fig31.jpg