Mines of the Argo
Central City, Colorado

The Argo Tunnel & Mill

Introduction: The Argo Tunnel

Sam Newhouse was the kind of man that moved to a grungy mining town after earning a law degree to find his fortune. He did.

Building Argo

He moved from Philadelphia to Leadville, Colorado where he organized transportation and supply chains for several mines and camps. After finding much success in the venture, he moved to Denver where he began to hear about ‘Golden Gilpin’—the county where riches in gold and silver were found and lost in flooding mine shafts. Not only that, but the hoists of the day struggled to lift rock cars from the deepest mines, which were often over 1,000 feet deep. Newhouse began to scheme how to fix both problems with one simple solution, a grand tunnel.

The whole district of mines could be drained by one central tunnel, Newhouse reasoned, and by 1891 and with $2 million in capital, the Argo Mining, Drainage, Transportation, and Tunnel company was formed. Though the official name of the tunnel is the Argo, it is often referred to as the Newhouse Tunnel, even today. By the time it reached Gunnell Hill in 1910, the project had cost about $5 million and measured almost 22,000 feet long.

Some of the mines that connected to the Argo were: Gem, Sun and Moon, Morning Star, Frontenac, Pozo, Saratoga, Calhoun, Mammoth, Gardner, Prize, and Grand Army.

Pozo Mine, the most menacing mine building I’ve ever seen. Black and white film, shot with the Fuji GX680, a beast of a camera.

Draining… The Bank

The tunnel was 12 feet wide throughout the first 2.5 miles of the tunnel and carried two tracks, where electric locomotives pulled ore from collection shafts to Idaho Springs.

News that Prize was connected to Argo, from a Colorado School of Mines Alumni Magazine.

From there to Gunnell, there was one set of tracks with ample room on the sides for drainage. Without their connections to the Argo, the hundreds of mines that connected to it would have closed by the 1920s because of flooding. Considering this fact, it is strange to note that the tunnel was such a colossal business failure. Newhouse’s company never negotiated proper payment from the mines it connected to. After all, if a mine was late in payment, or chose not to use the tunnels to transport ore and only used it as a sump, they could hardly plug the connection against thousands of gallons of water.

In an attempt to recoup losses, Newhouse raised more capital to construct a concentrator at the portal of the Argo Tunnel. The Argo Mill was a convenient choice for mining companies, as it meant they would not have to fight gravity to get their ore milled. Low grade ore that would not have been profitable to hoist and haul by railroad was suddenly profitable.

A map showing the Argo Tunnel in relation to the places I mention in this article. Click to enlarge.


On January, 19th, 1943, a group of miners as attempting to connect the flooded workings of the Kansas Shaft, near Nevadaville, to the Argo to drain them, when disaster struck. They accidentally released the pressure of the flooded workings into the tunnel and were crushed to death by the water and other contents of the mines above. Minutes later, a geyser ripped through Idaho Springs. Accounts describe it as a fire hose that took hours to run dry. The accident permanently closed the tunnel and mill, thus closing most of the mines in the district.

Today, the mill is preserved and open to tours (I highly recommend it) and the tunnel is part of an ongoing environment cleanup. Not too far into the tunnel is a thick steel bulkhead holding back millions of gallons of toxic mine drainings, which is slowly fed to a new dedicated treatment plant.