At one point, before the beginning of yesterday's march on the Mall to honor Martin Luther King Jr.'s birthday and to urge that Congress make it a national holiday, a group of teen-agers was shouting, "Holiday! Holiday! Holiday!" That offended another teen-ager, who was carrying a heavy sign mounted on wood. "This demonstration should be doing more things to motivate the crowd around things like jobs. We have more folks than ever today standing on the corners with no work--even though those are the things that King fought for," he said.

The young man with the sign had a point.

The thousands of marchers who turned out yesterday were rightly filled with pride as they trooped down the Mall through the snow, bundled snugly against the sharp wind that sliced into their cheeks. "This is a brilliant effort," said a middle-aged man in the undulating crowd.

But I couldn't help wondering if the marching and the rhetoric that came later in the day are enough in these economic hard times.

For as significant as it is to make Martin Luther King's birthday a holiday, Reaganomics has brought home the fact that these days, a march without a focal point of securing some cures to today's economic ills has something missing.

T hose who marched seemed to be T aware of their power as the size of the crowd swelled. By the time they reached the Capitol steps, they seemed on familiar terms with the power of unity King trusted and loved. In the midst of that power and unity, it was unsettling to see teen-agers hauling cassette stereos on their shoulders as they bounced to the latest tune. It was difficult to take their support of the holiday seriously.

The significance of yesterday's events should not be demeaned. The crusade to make King's birthday a holiday, led primarily by singer Stevie Wonder, should be applauded. Such a holiday would be a tremendous symbolic victory. It would bring black people dignity and self respect, and perhaps motivation to do other things as well.

Still, something seemed to be missing during yesterday's march. Perhaps it was a problem of expectation. This winter march and the Congressional Black Caucus legislative weekend in the fall have become the two biggest national gatherings of black America. In both, perhaps we are looking for something that no gathering or demonstration can deliver--economic progress.

Stevie Wonder should be given his due here; he understands the limitations of the day: "I just really feel we don't have enough reminders of a necessity to be right on," he said earlier in the week. "We have not had a day that recognizes a necessity for the kind of contribution that has to be made for us to keep in the direction of the positive . . . . Dr. King was far bigger than the physical manifestation of himself, you know. That is why he's living on in our minds, because we know that what he's talking about reminds us of our responsibility."

S o in a sense, the march is a S responsibility and a celebration of certain principles. But I suspect that King would be the first to say that even this much deserved holiday, once it is accomplished, will be meaningless to people who are on a permanent holiday of unemployment and whose bellies are empty.

So there has to be some way to make the true stuff of King's dream part of the ongoing program of black progress, and at this juncture in history, more than any other in the last 20 years, the stuff of King's legacy is economic progress and empowerment for black people.

When Martin Luther King died on April 4, 1968, he had already identified the critical issue of the next decade--economic justice. "Martin always knew that was the bottom line," his widow, Coretta Scott King, told me the other day. "But he knew it was always the most difficult."

Those who are committed to King's ideals could best show the thousands who demonstrated yesterday, here and throughout the nation, that the dream is not deferred by working together to bring about economic progress. That's the new frontier