Mountain Diesel Transportation locomotives 1510 and 1512, EMD FP7s, in Laramie Wyoming. MDT ran passenger excursion trips from Laramie to Walden, Colorado, 92 miles over a Union Pacific branch line. Early diesel locomotives, such as these (originally built for the Alaska Railroad), became popular with rail enthusiasts as they attained "vintage" status in the 1980s. However, the popularity of MDT's trips in a remote and sparsely-populated part of the country was short-lived and the operation ceased after only a few seasons. The locomotives, however, survive and continue to pull passenger excursion on the Verde Canyon Railroad in Arizona.