A steam locomotive thunders across a spindly wooden trestle high above a tunnel portal cut into Colorado's rust-red mountain rock — this hand-colored pre-linen gem captures one of the most dramatic engineering feats of the early twentieth century. The Denver, Northwestern & Pacific Railway, popularly known as the "Moffat Road" after its founder David, was carved through the Rockies beginning in 1903, and the famous "Loop" near Rollins Pass allowed trains to gain elevation by literally spiraling back over themselves — a tunnel below and a trestle above the same ridge simultaneously. Patches of snow cling to the shadowed slopes, evergreens dot the hillside, and a plume of black smoke from the locomotive's stack drifts into an azure sky, giving the scene an almost painterly drama. The numbered caption "9305" and the hand-lettered legend Looping the Loop on the Moffat Road Colorado anchor the image in the golden age of American mountain railroading.