EMD’s GP20 series was developed out of Union Pacific experiments with turbocharging GP9s. But it was Santa Fe that, starting in 1960, ordered 75 of the new 2,000-hp units, more than any other road and twice as many as UP. Here, on July 8, 1967, Santa Fe 1144 climbs the Joint Line southbound near Castle Rock, Colorado. The units were evidently a success: The 1144 will survive late into the 1990s as BNSF 2029, long after UP’s GP20s have gone to scrap.
