For the 50th year in a row, runners competed in the Run the Rockies road race last weekend, feet slamming into the pavement on Main Street in Frisco beneath crisp, early-autumn skies. But the race — which was held on Saturday, Sept. 19 — has changed time and time again over the last half-century. Since the first Run the Rockies race in 1977, the race has changed locations, organizers, dates and more, but, organizers say, the spirit of the race h…