National Audio

National Audio Company in Springfield, Mo., is the last U.S. manufacturer of these wondrous rectangles-and thanks to new interest from millennials in the "warm analog sound," the company is making more tapes than it ever has. Even in the dark days of the late 1990s, when CDs ruled, cassettes still held appeal in the spoken-word community. That and a market for blank tapes kept National Audio going. The company bought out other manufacturers and their equipment over the years, using "orphan" machines for parts.