|The Hoosac Mountain Tunnel was the first major rock tunnel in the United States. The Hoosac Mountain of the Berkshire Hills is located just East of North Adams, Massachusetts. The tunnel measures 4.75 miles long and took 24 years to complete. It was begun in 1851 under the direction of Herman Haupt and was finally completed in 1875 by W. and J. Shanley of Montreal.
The tunnel provided a rail connection between Boston and upper New York state. It was the first tunnel in which nitroglycerine would be used and was also significant in the development of compressed-air drilling machinery.