Undated (AP) _ Thousands of people lined up for today's Rose Parade - and several hundred were arrested - after Americans welcomed 1987 and the 200th birthday of the Constitution with gunfire and fireworks, alcoholic and alcohol-free toasts and wishes for peace.

An estimated 300,000 people jammed New York City's Times Square as the ''Big Apple'' dropped for the 78th time in 80 years, another 20,000 watched as Philadelphia opened the Constitution's birthday party, and thousands gathered across the nation to meditate, sing and cheer for peace in an observance that coincided with the end of the United Nations' International Year of Peace.

A ''family-oriented'' crowd in Washington, estimated by police at 150,000, gathered on Pennsylvania Avenue for the nation's capital's traditional celebration outside the historic old Post Office building.

City officials barred the sale of alcohol after a rowdy crowd a year ago ushered in 1986 with numerous fistfights, arrests and the rape and murder of a yougn woman. This year, with only hot dogs and hot chocolate served, police reported only four arrests on minor charges.

The last night of 1986 was the First Night in Boston, San Francisco, Albany, N.Y., Milwaukee and Charlotte, N.C., as thousands of people celebrated the New Year with alcohol-free gatherings.

Police in Pasadena, Calif., confiscated couches placed on the route of today's Rose Parade as thousands of people camped out for the extravaganza of 59 floats decorated with 6 million flowers.

''This is the public party zone,'' said Eric Stonecipher, 17, of Arcadia, Calif. ''This is the best place to be.''

By 7 a.m., 415 people were arrested, including 345 adults and 70 juveniles, mostly for being drunk in public, Pasadena police spokeswoman Maria De Robles said. A total of 550 people were arrested last year.

About 1 million spectators and a worldwide TV audience of 350 million are expected for the parade, which is to be followed by the Rose Bowl football game between Michigan and Arizona State.

But the forecast of sleet, rain and high winds in Philadelphia forced the postponement of today's 87th Mummers Parade, the nation's oldest organized parade. The parade has been rescheduled for Saturday, when participants competing for more than $300,000 in prizes will strut up Broad Street in huge and gaudy costumes of sequins and feathers.

Meanwhile, a wind-driven rainstorm Wednesday night cleared just in time for NBC to start its national coverage of the King Orange Jamboree Parade in Miami leading up to the Orange Bowl game.

Hundreds gathered Wednesday in San Francisco and Moscow to exchange greetings over a satellite hook-up. ''We think the more people communicate directly with each other, the greater the chance we will reduce tensions between the two political systems,'' said organizer Joel Schatz.

Police stepped up drunken-driving patrols overnight while scores of communities offered party-goers black coffee and free rides home.

An estimated 300,000 screaming, horn-blowing revelers elbowed their way into Times Square as an illuminated, 200-pound globe resembling a big apple descended 430 feet at midnight. Firecrackers echoed, champagne flowed, strangers hugged and lovers kissed 1986 goodbye.

Fireworks lighted the sky over the Benjamin Franklin Bridge connecting Philadelphia with Camden, N.J., beginning the bicentennial celebration of the Constitution, signed at Independence Hall on Sept. 17, 1787.

An estimated 20,000 watched the 14-minute fireworks salute.

In New Orleans, far fewer than the anticipated 100,000 jamed the lower French Quarter.

Nine members of San Francisco's zany Committee Against the End of the Month marched outside City Hall on Tuesday in an unsuccessful bid to keep 1986 around a while longer. ' 'Just say no to 1987,'' they chanted.

About 500,000 revelers surged through clear, cool weather into Boston to gawk at ice sculpture, art and a parade in the 10th annual alcohol-free mix of food and entertainment that has spread to other cities.

Police in New York assigned 1,970 officers to Times Square, 700 more than usual, to watch for any racial incidents triggered by an attack on blacks by whites last month that left one man dead. No racial unrest was reported.

Sgt. Raymond O'Donnell reported 34 arrests at Times Square. One man was shot in the arm and hospitalized in good condition, he said.

About 4,000 joggers ran around Central Park at midnight and stopped at ''water stations'' along the way for champagne.

One hundred people paid a sky-high tab - $799 - to jet nowhere quickly in a Concorde. After a few circles aloft, they returned to New York and zipped over to swank Regine's for champagne, dessert and circles on the dance floor.

Although Detroit and Los Angeles police had warned revelers against the traditional heralding of the New Year with gunfire, authorities in Southern California said several people were injured by falling bullets.

''It was like World War II down here (at midnight) as far as rounds being fired off,'' Santa Ana police Corp. Dick Stranberg said today.

In Los Angeles County, New Year's Eve revelers firing guns were blamed for the injuries of two adults, and police were investigating the possibility that a 9-year-old girl struck in the neck also was the victim of a celebrator.