Driving in the United States can be extremely confusing. Because states are allowed to enact their own traffic laws on state roads (though Interstates are centrally controlled by the federal government), driving between states can mean different driving rules.

Whenever you travel, it's a good idea to make sure you know the driving laws of the country that you're going to. But when travelling to the US, you need to make sure that you know the driving laws of all the individual states that you're visiting. Drink driving laws in the US are generally far more lenient than inside the European Union, with higher blood alcohol limits than in most European countries. The punishments for exceeding these limits are extremely harsh though, and can vary by state from having your license revoked to having your car taken.

The US has two blood alcohol limits. State by state the legal blood alcohol limit varies between 0.08 percent and 0.10 percent. Blood alcohol levels in the US are always stated as a percentage. A limit of 0.08 percent, for example, means that for every ten thousand parts of blood, eight parts are alcohol. (0.08% corresponds with the UK limit of 0.8g per litre)

States with 0.08% Limit                                  

The states that limit you to a 0.08 percent level of blood alcohol are the following: Alabama, Alaska, Arizona (for personal drivers, the limit for commercial drivers is 0.04 percent), Arkansas, California, Colorado, the District of Columbia (Washington D.C.), Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Missouri, Nebraska, New Hampshire, New Mexico, North Carolina, Oklahoma, Oregon, Rhode Island, Texas, Utah, Vermont, Virginia, Washington, Wisconsin and Wyoming.

States with 0.10% Limit

States limiting you to 0.1 percent are Connecticut, Delaware, Michigan, Minnesota, Mississippi, Montana, Nevada, New Jersey, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee and West Virginia.

How Many Drinks

It's important to remember that there can be no guideline for how many drinks will give you a certain blood alcohol level. Blood alcohol percentage depends on weight, height, sex and whether or not you have eaten. For example, two drinks will give an average hundred kilo man a blood alcohol percentage of about 0.03 percent.

Two drinks will give an average sixty four kilo woman a blood alcohol percentage of 0.07 percent. The amount of alcohol absorbed into your blood stream is subjective and depends on your body type. However, the limit of every state will allow an adult to have one drink. And as long as you weigh over around forty five kilos, every state's legal blood alcohol limit will allow you to have two drinks.

Drink Sizes

You must remember, however, that a drink is one unit of alcohol, and bars and restaurants rarely serve alcohol in single measures. A half litre beer will set you back two alcohol units, not one as you may believe. Serving size is not indicative of the number of units of alcohol a drink contains.

Despite having rather high blood alcohol limits compared to European countries, it is not a good idea to drink and drive in the United States.

Zero Alcohol

The best, and safest, plan is always just to drink nothing. That way you have nothing to worry about. Alcohol, even just one drink, will lower your reaction time, and could cause an accident. And one drink isn't really worth having an accident for. However, due to city planning in the US it is rare to find a bar or restaurant within walking distance of where you are, with the exception on in very large cities such as New York. Therefore, it's common for people to drive to bars. Traditionally, Americans have a designated driver when they go out drinking, a person who drinks no alcohol and drives everyone else home.