Western Massachusetts, known colloquially as "western Mass," is a region in Massachusetts, one of the six U.S. states that make up the New England region of the United States. Western Massachusetts has diverse topography; 22 colleges and universities including UMass in Amherst, MA, with approximately 100,000 students; and such institutions as Tanglewood, the Springfield Armory, and Jacob's Pillow.

The Springfield Armory, more formally known as the United States Armory and Arsenal at Springfield located in the city of Springfield, Massachusetts, was the primary center for the manufacture of United States military firearms from 1777 until its closing in 1968. It was the first federal armory and one of the first factories in the United States dedicated to the manufacture of weapons. The site is preserved as the Springfield Armory National Historic Site, Western Massachusetts' only unit of the national park system. It features the world's largest collection of historic American firearms.