These black 50 ft. steel-side, 14-panel gondolas with fi xed ends have the multi-color, circular, Rio Grande Main Line Thru the Rockies logo, lettering in white and run on black Barber? roller bearing trucks. The D&RGW served mainly as a transcontinental bridge line between Denver, Colorado, and Salt Lake City, Utah. It was a major origin of coal and mineral traffi c with a motto of ?Through the Rockies, not around them.? The Rio Grande was the epitome of mountain railroading, operating the highest mainline rail line in the United States with an elevation over 10,240 ft (3121 m) at Tennessee Pass.