The Harpers Ferry Armory, more formally known as the United States Armory and Arsenal at Harpers Ferry, was the second federal armory created by the United States government; the first was the Springfield Armory. It was located in Harpers Ferry, then part of Virginia, which since 1863 has been part of West Virginia. It was both an arsenal, manufacturing firearms, and an armory, a storehouse for firearms. Along with the Springfield Armory, it was instrumental in the development of machining techniques to make interchangeable parts of precisely the same dimensions.