The first articulated four-wheel drive tractor was built by Wagner Tractor of Portland, Oregon. The Wagner brothers had been building machinery for logging and mining since 1922 and entered the agriculatural market in the 1950s. John Deere and Wagner entered into deal in the late 1960s. At the time there was still not a large demand for the big tractors, and only 51 were purchased by Deere. Deere re-entered the market with their own tractor (the 7020) in 1971. A five-year no-compete clause in the contract left Wagner unable to build tractors and ended Wagner in the agricultural market.
Big Tractor Power - site dedicated to high-horsepower four-wheel-drive tractors
WagnerTractors.com - site specific to Wagner and Wagner-built tractors