The trees in Washington may still be bare, but there was lots of glorious spring green here anyway yesterday. Most of it was worn by people.

A crowd estimated by police at more than 120,000 lined up along Constitution Avenue to watch what has become an unexpected tradition in this town; the St. Patrick's Day Parade.

"Tenacity," is how Tom Reilly, a Rockville resident and parade official, explained the way the area's Irish have worked to put a little local zip into their beloved celebration.

Recalling the time just seven years ago when a small but dedicated group of 200 had marched up Massachusetts Avenue to sing songs at the statue of Irish patriot Robert Emmett, Reilly was clearly pleased with the parade's transformation.

"They're been pushing and working on this for years," he said, while behind him in front of the reviewing stand passed just some of the bands, floats, dancers and other participants who dazzled enthusiastic spectators at the three-hour event.

Most of the Irish and non-Irish who watched yesterday's parade came dressed for the occasion. They worn green hats, green ties, green "Kiss Me," I'm Irish" buttons and Irish banners, their Irish wolfhounds and Irish setters and, of course, their beer.

"The only think missing is green beer," complained Thomas Reilly - another Tom Reilly, who with his wife, Rosalie, had driven in from Arlington to see the parade. "I brought my own coffee . . . ho, ho, ho," he said, holding up a thermos.

Thought the skies overhead had been cloudy all morning, a few of the spectators bothered to bring umbrellas.

"It's not going to rain on the Irish," Reilly explained. He was right.

In fact, a bright sun enveloped the parade route just as it was all getting under way at about 2 p.m.

"St. Patrick never lets you down," boasted Michael Keane, who said he came here from Dublin a year ago to help a youth counseling center in Rockville. He was selling raffle tickets for the project among the crowd.

Jean Peelen said she has not missed the St. Patrick's Day parade here in three years, ever since she and some friends stumbled across it accidentally.

"Now I come to the parade every year and then go to the Dubliner," she said, referring to a popular drinking and Irish music spot on Capital Hill.

None of Peelen's comments would seem remarkable except for the fact that she is a law student in Tuscaloosa, Ala., and makes her traditional trek from there to Washington every year just to celebrate St. Patrick's Day in Washington.

"I don't think there are any Irish in Tuscaloosa," she lamented.She plans to move here in the fall.

This year's parade, using the theme "America First, officials present. Mayor Walter E. Washington was a participant as was the city's new police chief, Burtell Jefferson, who drove himself in the procession. The man he replaced, retired former chief Maurice Cullinane, served as the parade's grand marshal.

Dennis and Dody Breen of Hyattsville attended for the second year in a row. They brought along their son, Daniel Patrick, who is 2 1/2 years old and whose great grandparents on his father's side were born in Kilkenny and Wexford counties in Ireland.

For Bonnie Hardy, who's "not Irish myself," the parade "is a great outing. It brings a lot of people together whether they are Irish or not. "It's sort of a celebration of spring todya." She and a friend rode their bicycles to the parade, bringing along Hardy's two small children.

There was no trace yesterday of the brief political controversy that had threatened to distract from the celebration earlier in the week.

Patrick Cardinal O'Boyle, the retired archbishop, had withdrawn his name as a parade patron at the urging of the Washington Cathedral's Canon Michael Hamilton. The latter objected to the parade participation of a group Hamilton accused of supporting the Irish Republican Army. But the group, which claimed it only aides the families of political prisoners in Ireland, said it never intended to march in the parade, and O'Boyle soon rejoined the list of parade patrons.

"We're not involved in politics," Reilly, the parade officials, insisted. "There's only one Ireland, and that's where the people lived and where our forefathers were born."

A major element in the parade's growing popularity has been the support of the area's local Irish taverns, some of whom sponsored floats for the event.

Lil ("my maiden name was Shannon") Palm operates Mike Palm's restaurant and "was one of those pushing for it (the parade)."

The Pierce Street Annex piled a lot of its customers into an Irish double decker bus and joined the parade's lineup. A sign on the back invited the spectators to come "party" there afterwards.