America, its Bicentennial year now only a memory, celebrated its 201st birthday yesterday with a leisurely, largely subdued, seemingly haphazard kaleidoscope of ceremony, summer outings, patriotism, picknicking, parades, some social protest and fireworks.

A modest mid-day ceremony at the National Archives here formally put to rest some official mementos of the Bicentennial as lid was sealed on all aluminum time capsule containing such souvenirs as a register signed on July 4, 1976, by then-President Gerald R. Ford. It is meant to be opened in time for the Tricentennial in 2076.

By evening, crowds began pouring onto the Washington Monument grounds for Washington's annual fireworks display. During the day, the Metro system's special holiday subway service encountered numerous delays as Independence Day sightseers, many of them out for a ride on the newly opened Blue Line between northern Virginia and downtown Washington, jammed subway cars.

Ceremonies and holiday spirit - though modest in comparison to last year's extravaganzas - filled the nation yesterday. New York's harbor was dotted with sailing boats in a small-scale reenactment of last year's procession of tall ships.Philadelphia awarded its freedom medal to entertainer Frank Sinatra. Parades were everywhere.

President Carter announced yesterday he is awarding the Presidental Medal of Freedom, the nation's highest civilian award, to the late Rev. Martin Luther King Jr., the Nobel peace prize winner and civil rights leader, and to Dr. Jonas E. Saik, developer of polio vaccine.

Some social protest also cropped up here and there, ranging from a marijuana smoke-in by several thousand of the drug's advocates in Lafayette Park here to a clash in Columbus, Ohio, where a black group, chanting "Ku Klux Klan, scum of the land," rushed the podium of an Independence Day Klan rally called to protest proposed school basing. Highway Patrol troopers broke up the Columbus fracas (Story, Page A3.)

In Washington, the ceremonial trappings included an all-black fife and drum corps, whose slogan is "we have a dream," as well as an all-white volunteer Revolutionary War regiment from Virginia, whose members fired flintlock guns and a three-pound cannon.

A parade along Constitution Avenue - a hybrid of the traditional and the unorthodox - began with military groups in dress uniforms. It also included a "Drugmobile" sponsored by the D.C. Department of Human Resources, marchers who passed out announcements for a Washington Diplomats soccer game, a truck sponsored by the left-wing U.S. Labor Party and an auto bearing signs supporting D.C. City Council candidate Barbara Sizemore, the controversial former city school superintendent.

"Not that much went by," Alan Krauss, a Chicago physicist, said after watching most of the brief Constitution Avenue parade. "But I couldn't make out what most of the groups were."

On a near-broding day here, relaxation was the mood as much as ceremony. People sprawled in the shade, flocked to nearby beaches, went bicycle riding, bought balloons, watched puppet shows and jazz concerts sponsored by the Smithsonian Institution's Museum of History and Technology, ate hot dogs and watermelon, drank beer and lemonade, and jogged across the Mall.

Ken Konetski, assistant product manager here for an electronics firm, sat in the shade of a tree beside Constitution Avenue, reading a thick book on taxation as the parade passed by, "Nice day," he said, "I wanted to relax. I like parades. It all worked together."

Nearby, the Tripoli family from Burke - Sal, a systems engineering manager for IMB Corp., his wife Nancy, a doctoral candidate in clinical psychology at Catholic University and their 9-year-old daughter, Valli - sat on the grass, eating a picnic lunch. They had parked their car near the Pentagon, they said, and had biked in the rest of the way to go to Smithsonian concerts and watch the parade.

Yes, they agreed, this year's July 4 celebrations were more subduced than last year's. "This is provincial as opposed to the mad mob scene last year," said Sal Tripoli, "This could have been Podunk, Iowa, today." Yet they seemed pleased with the calm mood. "I don't mind the fact that this is not the national gala," Nancy Tripoli added.

Yesterday also was a day for neighborhood gatherings as much as official events. Communities joined together to watch and march in local parades with bagpipes and drum majorettes in Hyattsville. Takoma Park, Northwest Washington and hundreds of other spots here and across the nation.

Wade Hubbard was bare-chested and draped with a chain as he pulled his daughter on a cart in a neighborhood parade along McArthur Boulevard NW. "I'm a slave to my daughter," said Hubbard, "She is a women's libber." Mary, his 9-year-old daughter, was seated in a chair atop the cart, decked out with posters saying "Women's Liberation."

The MacArthur Boulevard procession was said by its observers to have drawn as many as four generations of some families to its ranks.

Takoma Park's 88th annual Independence Day parade was made up of 70 floats, several military marching units and some local governments officials, John Roth, Takoma Park mayor who rode in a 1910 International Harvester Auto. "I've been watching this parade for 25 years." Barbara Hudson, a Beltsville resident, remarked, "It's tradition. Everyone comes."

Hyattsville's parade ended, like many of yesterday's doings, with picnicking, softball and an amusement park ride - this one called The Whip. The local boys' and girls' club set up a stand to sell barbecue chicken.

To commemorate the day with fitting ceremony, the Declaration of Independence was read from the steps of the National Archives. Glenn Taylor, an actor dressed in 13th century attire including a white win, intoned the declaration into a battery of television microphones before an audience of hundreds - far fewer than attended the same observances last year. Listeners from various states broke into applause as Taylor read the list of states represented by the declaration's signers.

Then came the sealing of the time capsule, filled with relies of the Bicentennial. "This caps the Bicentennial," said Benjamin Rhuef public information officer for the Archieves.

Into the time capsule went the pens used by former President Ford, former Vice President Nelson A. Rockefeller, former Speaker of the House Carl Albert, and Chief Justice Warren E. Burger when they signed a Bicentannial register on Independence Day last year.

Also into the capsule went the first page of the register, two microfilm copies of the remaining 788 pages of the register bearing more than 25,000 other signatures, copies of the July 4, 1976, editions of The Washington Post and The Washington Star, a flag that was flown on July 4, 1976, on Guam, and an assortment of other items.

Though the capsules lid was tapped shut with a rubber mallet, the capsule was not fully readied for storage even yesterday, a year after the date that gave significance to most of its contents. Argon gas must still be pumped into the capsule to help protect the momentos from oxidation.

The marijuana smoke-in at Lafayette Park across Pennsylvania Avenue from the White House was sponsored by a coalition supporting legalization of marijuana including the Youth International Party, known as the Yippies, and the national Organization for the Reform of Marijuana Laws, called NORNI. Though marijuana smoke at times filled the air and a few minor incidents occured, police reported they had made no arrests.

"With the numbers they have, (estimated at upward of 3,000) the policy is to control the crowd," said Deputy U.S. Park Police Chief Parker T. Hill, "We're not concerned with minor infractions." Arrests, he added might have led to further incidents.

The marijuana demonstrators listened to rock music, bathed in fountains, tossed Frisbees, occasionally taunted the police, displayed protest signs and climbed atop a park statue. Some also smoked marijuana.