The BAC limit is 0.08% in United States - this applies to both visitors and residents. Your BAC level is a measurement of the percentage of alcohol in your bloodstream. This information is used to determine how inebriated an individual is. Driving a vehicle with a BAC higher than 0.08% is against the law in United States and you will be deemed as ‘driving under the influence’. Keep in mind that there are stricter penalties for those who drink-drive and are under the legal drinking age. In United States, you must be at least 21 to drink.