More than two decades after the United States established a uniform legal drinking age of 21, some states are looking at lowering the age as low as 18 in certain circumstances.

Vermont is the latest state to formally explore the issue. The state senate has approved a bill to have a task force weigh the pros and cons of rolling back the drinking age.

Proponents of the measure say the current law doesn't work and forces young people to binge drink outside of the public eye.

Mothers Against Drunk Driving and others claim a lower drinking age would be foolish to consider. They say the 21-year-old age limit has saved thousands of lives since it was enacted in 1984.

The law requires states to set the drinking age at 21 or lose U.S. federal government transportation funding.

Group uses social networking to lobby for lowered age

In South Dakota, a bill has been drafted to allow 19- and 20-year-olds to legally buy beer no stronger than 3.2 per cent alcohol.

In Missouri, a group is using the internet social networking sites Facebook and Meetup to try to collect more than 100,000 signatures to get a measure on the ballot to lower the drinking age to 18.

In South Carolina and Wisconsin, lawmakers have proposed allowing active duty military personnel younger than 21 to buy alcohol.

A similar proposal was rejected last year in New Hampshire.