2 Tunnels to explore in United States
Third largest and third most populous country in the world. Size-wise, it is almost as large as the continent of Europe.
Argo Gold Mine & Mill is a national historic site located about 45 minutes from Denver. featuring an intact gold mill built at the entrance of the Argo Tunnel. The tunnel was built between 1893 and 1910 to drain the gold mines in Virginia Canyon, Gilpin Gulch, Russell Gulch, Quartz Hill, Nevadaville, and Central City and allow easier ore removal. It began in 1893 with the construction of the Argo Tunnel. After 17 years it reached Central City, about 4.5 miles away.
The Mule Pass tunnel, Believed to be the longest tunnel in Arizona. Locals call it "The Time Tunnel". Mule Pass Tunnel created a new gateway into Bisbee. It also cut 10 minutes off the drive over the 6,030-foot-high pass on US 80 into the southeastern Arizona mining town. The road is now known as State Route 80, and the Highway Department is now the Arizona Department of Transportation.