The “easy” part of building the Greenfield-Troy Railroad was laying track from Greenfield, Massachusetts, along the natural cut the Deerfield River formed as it flowed through the valley. The true challenge was cutting through Hoosac Mountain, which lay directly in the path of the proposed railway route. Workers had to drill through 4.75 miles of solid rock. They began chipping away in 1854, armed only with hammers, hand drills, and black powder. Little progress was made until the invention of the compressed air drill and trinitroglycerin (TNT) in the 1860s. This unstable explosive generated a blast 13 times more powerful than the black powder it replaced. Almost 200 men lost their lives during construction of the Hoosac Tunnel.