spirits, but most brands are produced in Kentucky, where bourbon production has a strong historical association. The filtering of iron-free water through the high concentrations of limestone that are unique to the area is often touted by bourbon distillers in Kentucky as a signature step in the bourbon-making process. On August 2, 2007, the U.S. Senate passed a resolution sponsored by Senator Jim Bunning (R-KY) officially declaring September 2007 to be National Bourbon Heritage Month, commemorating the history of bourbon whiskey. Notably, the resolution claimed that Congress had declared bourbon to be "America's Native Spirit" in its 1964 resolution. However, the 1964 resolution did not contain such a statement; it declared bourbon to be a distinctive product identifiable with the U.S. (in a similar way that Scotch is considered identifiable with Scotland). The resolution was passed again in 2008. As of 2018, approximately 95% of all bourbon is produced in Kentucky, according to the Kentucky Distillers' Association. As of 2018, there were 68 whiskey distilleries in Kentucky, this was up 250 percent in the past ten years. At that time, the state had more than 8.1 million barrels of bourbon that were aging – a number that greatly exceeds the state's population of about 4.3 million. Bardstown, Kentucky, is home to the annual Bourbon Festival held each September. It has been called the "Bourbon Capital of the World" by the Bardstown Tourism Commission and the Kentucky Bourbon Festival organizers who have registered the phrase as a trademark. The Kentucky Bourbon Trail is the name of a tourism promotion program organized by the Kentucky Distillers' Association that is aimed at attracting visitors to the distilleries in Kentucky, particularly Four Roses (Lawrenceburg), Heaven Hill (Bardstown), Jim Beam (Clermont), Maker's Mark (Loretto), Town Branch (Lexington), Wild Turkey (Lawrenceburg), and Woodford Reserve (Versailles). Tennessee is home to other major bourbon makers, although most prefer to call their product "Tennessee whiskey" instead, including giant Jack Daniel's. It is legally defined under Tennessee House Bill 1084, the North American Free Trade Agreement and at least one other international trade agreement as the recognized name for a straight bourbon whiskey produced in Tennessee. It is also required to meet the legal definition of bourbon under Canadian law. Although some Tennessee whiskey makers maintain that a pre-aging filtration through chunks of maple charcoal, known as the Lincoln County Process and legally mandated since 2013, make its flavor distinct