September marks the sixth National Bourbon Heritage Month. Here, courtesy of Beam Inc and Kentucky Distillers' Association, are some facts on the US spirit, including its strict definition.

  • Bourbon must be produced only in the US
  • It must be made of a grain mix of at least 51% corn
  • It must be distilled at less than 160 proof (80% abv)
  • It must be aged only in new, charred white oak barrels
  • Water is the only additive permitted, which can be used to reduce the abv
  • 95% of the world's Bourbon supply comes from the state of Kentucky
  • Production of Bourbon has risen by more than 50% since 1999 – in 2010, production totalled 786,778 barrels
  • Total Bourbon inventory reached 4.7m barrels in 2010, reaching its highest point since 1982
  • Exports of distilled spirits from the US broke $1bn in 2010 for the fourth consecutive year. Kentucky Bourbon and Tennessee whiskey made up just over $700m
  • In 1840, the spirit being made in Old Bourbon County officially became known as Bourbon. Prior to this it was often labelled 'Bourbon County Whiskey' or 'Old Bourbon County Whiskey'
  • In 1964, an act of Congress declared Bourbon as 'America's Native Spirit' and the country's official distilled spirit