TRY AS IT has to preserve a reasonable legal drinking age of 18, the District of Columbia is being financially and politically whipped into raising the age to 21. Buffeted by Maryland, Virginia and the federal government, Mayor Barry has announced his support for the change. The D.C. Council will find the going much rougher than it was last year when the members killed a proposal to raise the drinking age of 18 for beer and wine. But we continue to believe that raising the age is an unfair approach to adults ages 18 to 21, who are not even, statistically, the most dangerous drivers in this city.

The difficulty is that Uncle Sam is calling the shots: under federal law, the District stands to lose about $7.8 million in federal highway funds over the next two fiscal years if the city doesn't conform to the higher drinking-age standard. Though Mayor Barry didn't cite this as a reason for his support of a change, he pointed to a need for a good-neighbor policy with Maryland and Virginia. "It is important that we not provide a haven for those young people who would use the District to obtain alcoholic beverages prohibited in the communities in which they live," the mayor said the other day.

That's fine, but why shouldn't those communities cooperate with the city in enforcing drunk driving laws instead of punishing an entire classification of people otherwise considered adults? Why should residents who are allowed to vote, to sign contracts and to serve in the armed forces be denied a bottle of wine over dinner or a six-pack with the ball game on TV? If ages and accidents are the criteria for determining drinking policies, the minimum age might better be at least 25.

Many excellent efforts are being made to curb drunk driving, including campaigns by students aimed at those who drink and then try to drive. That's more realistic and more to the point. But the District will be hard-pressed to remain a wet island given the mood of its neighbors and the federal government.