The Hoosac Tunnel is a 4.75-mile-long railway tunnel located in western Massachusetts. It was constructed between 1851 and 1873 and is part of the Boston and Albany Railroad. The tunnel was built to provide a direct route through the Hoosac Range, facilitating transportation and trade in the region. The construction of the Hoosac Tunnel was a significant engineering challenge, involving the use of dynamite and other techniques to excavate rock. It was one of the longest tunnels in the United States at the time of its completion and played a crucial role in the development of rail transport in the northeastern United States.