It is illegal to sell alcohol to anyone arriving on horseback.

The Law Explained

In Missoula, an old ordinance allegedly made it illegal for tavern owners to serve intoxicating liquors to patrons who rode their horses up to the establishment. This was likely an early attempt to curb 'drunk driving' and prevent inebriated cowboys from causing chaos in the streets. Bartenders had to ensure patrons were on foot before pouring a whiskey.