In 1927, the Denver & Salt Lake Railroad (later merged with the Denver & Rio Grande Western) completed the Moffat Tunnel in Colorado. The six-mile bore eliminated the treacherous main line over Rollins Pass, providing a shorter route from the Midwest to the Salt Lake basin.

In the nineteenth century, Denver had been bypassed by the Union Pacific, the first transcontinental railroad. While it grew to become the great city of the Rocky Mountain West, it had only roundabout lines westward across the mountains.

After lengthy court battles and bruising political fights, David Moffat was able to begin construction of the tunnel that bears his name. For three years, miners labored far beneath the blazing summer sun and frigid winter storms to carve a mainline railroad tunnel, through mostly solid rock, at an elevation of more than 9,200 feet above sea level. When the miners broke through in February of 1927, they had managed to drive two working faces 32,800 feet through the Continental Divide-and meet dead-on in the middle of the mountain.

Denver feted the men, holding a great parade and entertaining them at the Cosmopolitan Hotel. This was a symbolic triumph, for the 38-mile Dotsero Cutoff linking the line west of the tunnel with the railroad to Salt Lake City would not be finished until 1934. But it opened the way for a far easier crossing of the Rockies. The Moffat Tunnel today carries both Amtrak and freight trains.

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