Bourbon whiskey is a type of American whiskey, a barrel-aged distilled spirit made primarily from corn. The name ultimately derives from the French Bourbon dynasty, although the precise inspiration for the whiskey's name is uncertain; contenders include Bourbon County in Kentucky and Bourbon Street in New Orleans, both of which are named after the dynasty. Bourbon has been distilled since the 18th century. The use of the term "bourbon" for the whiskey has been traced to the 1820s, with consistent use beginning in Kentucky in the 1870s. Although bourbon may be made anywhere in the United States, it is strongly associated with the American South and with Kentucky in particular. As of 2014, distillers' wholesale market revenue for bourbon sold within the U.S. was about $2.7 billion, and bourbon made up about two-thirds of the $1.6 billion of U.S. exports of distilled spirits.