They marched down Constitution Avenue for four hours yesterday, brightly dressed groups from around the country, bands, officials and drill teams, swinging their arms, quick-stepping jump-stepping, maneuvering for prizes in front of the reviewing stand and infecting crowds with their spirit.

The Elks are here. Ten thousand of them march in style in a grand parade yesterday in front of some 20,000 people.

"We are a constructive part of black America, and this is our showcase event," beamed James R. Smith, public relations director for the Improved Benevolent Protective Order of the Elks of the World.

Many amoing the nearly all-black spectators shouted encouragement in a spontaneous burst of pride, fraternal and black. "All right, ALL RIGHT, pull it on up sisters," screamed Philip Coleman, 35, of Baltimore as an Elk drill team from Dayton pirouetted on the asphalt.

William C. Barton, exalted ruler of the 102 members of the Boston Elks, couldn't march because of his arthritics, but when his red and black clad drum and bugle team neared the reviewing stand at the end of a long march, pounding out a bongo beat, he limped out to lead the youngsters in his best Louis Armstrong manner.

"Look this way, Daddy," shouted his daugher, Louray, 17, as she followed behind the crowd, snapping pictures. "He's stepping out, isn't he.?"

The parade is part of the 78th annual convention of a group founded in 1998 because the B.P.O.E. refused to admit blacks.

Among those marching and watching yesterday were exalted rulers, daughter rulers and leading knights; chaplains and generals; brothers and daughters; the inner guard and the outer guard.

Some of them wore jewel-bedecked fezzes, white and khaki uniforms with gold piping, baseball caps with braid and purple epaulets, velvet collars with medalions set in initiation mother-of-pearl and wing-tip shoes painted gold.

Ten times a year Donald T. Jones, 51, an Elk who works as a chauffeur in Sarasota, Fla., pulls on the uniform of a colonel in the Antler Guard, Southern Division. Except for the patches, and the Elk on the cap, he looks like a full colonel in the U.S. Army, complete with eagles on the shoulder.

He patrolled the streets, yesterday between the crowd and the marching units, with an air of authority. Elk dom, he said "is everything to me."

Others fainted and had to be taken to Red Cross aide stations. By the parade's third hour many of the spectators laid down to rest along the lawns on Constitution Avenue.

The crowd, many of them friends and relatives of the participants, saved their warmest applause for the youth groups.

Most of the Elks have associations for youngsters ranging from age 3 to 21. Dressed in everything from T-shirts to jump suits, tennis shoes to Army boots, they were striving yesterday to show judges the results of weeks of practice drills.

When she had finished what seemed to her like a two-hor march, 12-year-old Tracy Reavis of Brooklyn took off her shoes and sat on the grass with her friends. "It started out fun," she said, examining her foot for blisters.

"Then I got tired, and then I got sick," She was glad her part was over, she said, and she slowly headed for a vendur to get an ice cream bar.