The Sutro Tunnel is a drainage tunnel (adit) connected to the Comstock Lode in Northern Nevada. It begins at Dayton, Nevada, and connects 3.88 miles (6.24 km) Northwest to the Savage mine in Virginia City, Nevada. The Sutro Tunnel pioneered the excavation of large drainage and access tunnels in the US. Later US mine drainage tunnels included the Argo Tunnel at Idaho Springs, Colorado, the Leadville and Yak tunnels at Leadville, Colorado, and the Roosevelt tunnel in the Cripple Creek district, Colorado.