This rail tunnel through the Berkshires, completed in 1875, connected eastern Massachusetts to the industrial and transportation centers in upstate New York and the Great Lakes. At the time of completion it was the longest tunnel in the world, at 4.75 miles, and nearly 200 lives were lost during its 25 years of construction, mostly Chinese laborers from San Francisco. It was also the first tunnel project to utilize nitroglycerine to blast, and compressed air to drill. It is still in use, though hardly the vital rail corridor it used to be.