[HurkinMcGurkin]

There is a federal law that states you must be 21 to drink.

No there isn't.

[Liberal Classic]

There's no federal law that raises the drinking age to 21. However, buried withing congressional transportation appropriation bills are riders which specify any state without a drinking age of 21 will not receive money highway funds. I believe Lousiania is the only state with an 18 drinking age.

[yonif]

No there isn't.

"The National Minimum Drinking Age Act is perhaps the law that has the most impact on the day-to-day lives of America's youth since it was signed into law on July 17, 1984."

(sources at the bottom)

http://www.asfar.org/zine/5th/cover.html