The word itself is not familiar to most people. A 'cooper' is a person who makes or maintains barrels and similar objects. A 'cooperage' is the place where that is done.
Cooperage is an ancient craft. It preceded the Iron Age but the advent of strong iron tools made it possible to work hard woods for many purposes, including barrel-making. Today, the craft is kept alive primarily by the wine and whiskey industries. Since only new barrels can be used to age bourbon and other straight whiskeys, American distilleries require a steady supply and cooperages are their essential partners.
Brown-Forman Cooperage in Louisville is one of the two main suppliers of barrels to bourbon makers. Their barrels are used for Jack Daniel's, Woodford Reserve, Early Times, Old Forester, and other Brown-Forman products.
The other big barrel-maker, which serves the rest of the industry, is Independent Stave Company. They make whiskey barrels in Lebanon, Kentucky, and (coincidentally) Lebanon, Missouri. They have other plants that primarily make wine barrels.
Brown-Forman Cooperage offers tours through Mint Julep Tours. Kentucky Cooperage (Independent Stave) in Lebanon, Kentucky, offers free walk-in tours twice a day.
The booming whiskey business has promoted some smaller players to enter the field, including Kelvin Cooperage in Louisville and the Barrel Mill in Minnesota.
Although barrel-making is still very labor-intensive, and some of that labor is highly skilled, the process is much more automated today than it was a century ago. At a place like Louisville's Hartmann Cooperage (1875-1925), where barrels were made almost entirely by hand, dozens of men would have performed the hard, physical labor using tools not much changed since the dawn of the Iron Age.
Henry Hartmann's grandson, Walter Doerting, prowled the cooperage as a child and ultimately inherited a large collection of its tools, which he donated to the Jim Beam Company. When you visit Jim Beam in Clermont, Kentucky, you can also visit the Hartmann Cooperage Museum.
In 1992, Doerting visited the museum, demonstrated some of the tools, and talked about his memories of the cooperage for the documentary "Made and Bottled in Kentucky," which is conveniently available for purchase in the right-hand column of this page.