Farmer Nick Welker ’s tractors steer themselves nearly as effectively as the latest Teslas. They were built in the 1970s. Welker has spent years outfitting the machines with satellite-guided steering systems, giving him cutting-edge technology without spending $700,000 for a new tractor. The last improvement two years ago on his 52-year-old tractor cost $20,000.

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Persons: Farmer Nick Welker, Welker