The most frequent misconception about bourbon is that it has to come from Kentucky, or has to come from Bourbon County. Not the case; in fact there are currently no operating distilleries within the Bourbon County. (Consider that your trump card on the drunk guy at the bar, who thinks he knows more about spirits than you do.)
But Kentucky certainly produces the lion's share. 95% of the world's bourbon is made in the state—and more than half of Kentucky bourbon is made by Jim Beam.
The white-label bourbon is a fixture on bars the world over. But that's not all Beam makes; other recognizable names including Knob Creek, Booker's, and Basil Hayden are also made by the company. All told, they produce more than 90 million bottles annually from their operation in Clermont, Kentucky.
Fine, Then, What IS Bourbon?
Bourbon need not be made in Kentucky, but it does need to be American-made. The distilled spirit is made from a grain mixture that must include at least 51% corn; the remainder includes rye, wheat, and/or malted barley. (In the case of Jim Beam, it's rye and malted barley. The most well-known wheated bourbon is Maker's.) When it's distilled, it has to be 160 proof or lower; when put into barrels, 125 proof or under. And those barrels have to be new charred American white oak. Once they've been used once, that's it. (Of course, they find other uses, most notably in aging Scotch.)
Like many venerable bourbons, Jim Beam is a family operation, now in its seventh generation. Founded in 1795 by Jacob Beam, the distillery was first known as "Old Tub," with whiskey selling by the name "Old Jake Beam Sour Mash." It remained in family hands until Prohibition, and was sold briefly as Jim Beam himself (the fourth Beam) went into coal mining. Upon repeal, the distillery was rebuilt within 120 days. It wasn't until 1943 that Old Tub became Jim Beam, the name it's sold under today.