NEW YORK, JUNE 20 -- Amid a blizzard of ticker tape and a crescendo of cheers, more than half a million New Yorkers gave Nelson Mandela a tumultuous welcome today as the South African black leader was feted by schoolchildren, embraced by political leaders and hailed as "a modern-day Moses."

In a moment of celebration that briefly seemed to erase the city's own racial tensions, the mostly black crowd, standing shoulder to shoulder with dark-suited Wall Street businessmen and a sprinkling of Hispanics and Asians, lined Broadway as Mandela smiled and waved from a peaked-roof plexiglass vehicle.

Vast bundles of shredded paper, some tossed from open windows and some from rooftops, rained down as the parade snaked along the 16-block "Canyon of Heroes."

The 71-year-old leader of the African National Congress (ANC), starting an eight-city U.S. tour that is to bring him to Washington Sunday for a three-day visit, arrived nearly two hours late from Montreal after organizers decided that he needed more rest.

Mandela, who aides conceded was tired, also canceled two evening events on what has mushroomed into a grueling schedule.

Today's emotional high point may have come when Mandela, introduced at City Hall by David N. Dinkins, New York's first black mayor, raised his right arm in a clenched-fist salute and was joined by many in a crowd that stretched in a broad arc from the Brooklyn Bridge to Broadway.

"Soon, our country, the land of apartheid and the worst form of institutional racism, shall be free," Mandela told the crowd. "We want our new South Africa to be a country which banishes forever racism in all its forms. . . . Apartheid is doomed! South Africa shall be free! The struggle continues!"

Along the parade route, there was a sense of awe about Mandela, whose long imprisonment has turned him into an almost mythic figure.

"I think he's a hero in the sense that not everybody would be willing to go to jail for 27 years, so I really think he's my Superman," said Schurbert Scrubb, 11, from the Bedford-Stuyvesant section of Brooklyn.

"We are both black. We are both from Africa. He could probably be my family."

Barbara Tatum, 52, a party planner from Brooklyn said she thought "there was a sense of brilliancy. To see everybody screaming and yelling, the enchantment on the faces and the togetherness. I've never seen so many different kinds of people in New York."

Praise was equally lavish from political leaders, including Gov. Mario M. Cuomo (D), who called today's celebration "the single most memorable thing I've ever witnessed."

Dinkins likened Mandela to "a modern-day Moses leading the people of South Africa from enslavement at the hands of the pharaohs. He and his people have endured their walk through the desert of deprivation."

There were a few discordant notes. Former mayor Edward I. Koch, one of 350 dignitaries on the City Hall podium, seemed less than enthusiastic.

"If I wanted to say something you want to hear, I'd say his physical presence is going to change race relations," Koch said. "I don't believe it, and neither do you."

Mandela began his 12-day U.S. visit by sounding his main theme, the need for continued U.S. sanctions against the white minority government in Pretoria.

In arrival ceremonies at John F. Kennedy International Airport, Mandela, speaking slowly in accented English, said he plans to tell President Bush when they meet Monday that the economic sanctions were imposed "for the purpose of dismantling apartheid" and that it was "no use" to demand change without such economic pressure.

Mandela, released from prison in February, struck an optimistic note, saying: "The chains of those who once hoped that they would remain forever the masters, with the blacks as servants, those dreams have been completely shattered by the actions of the people."

Mandela called U.S. support

for his cause "a source of tremendous joy and strength" after two schoolchildren presented him and his wife, Winnie, with scarves in the ANC colors of black, green and gold.

As a band played the ANC anthem, the gray-haired Mandela moved slowly through a single-file delegation that included Cuomo, New Jersey Gov. Jim Florio (D), Reps. Charles B. Rangel (D-N.Y.) and Major Owens (D-N.Y.), Jesse L. Jackson, singer Harry Belafonte, actor Bill Cosby and Mandela's daughter, Zenani.

About 10,000 people, many of them students, greeted Mandela with chants and waves when he arrived at the athletic field of Boys and Girls High School in Bedford-Stuyvesant. Speaking from a green tractor-trailer, Mandela appealed for donations to improve educational facilities for black South Africans, which he called "far inferior to whites'." He said the students' enthusiastic response here "cuts down my age by almost 25 years."

After a motorcade through Brooklyn, Mandela lunched at a Coast Guard station in Battery

Park overlooking the Statue of Liberty.

As 600,000 people poured onto lower Broadway and City Hall Park, a security effort dubbed Operation Topaz -- the strictest since the 1979 visit of Pope John Paul II -- used thousands of police officers, barricades, helicopters, boats and bomb-sniffing dogs to ensure Mandela's safety.

Ambulances were stationed along the parade route, and even potholes had been filled.

The procession featured marchers and bands representing Africans, Italians, Irish, Arab Americans, Germans, Polish, Chinese, Greeks, Brazilians, Scandinavians, Haitians, Dominicans, Kurds and Sikhs.

Eighty-five bags containing 150 miles of stock exchange-style ticker tape, a fading anachronism in the computer age, were handed out by a Connecticut firm, and more than 450 sanitation workers and 15 water trucks were deployed to clean up.

Nora Rushmore, 63, a Newark track and field coach, waited five hours with 15 of her students to see Mandela. "I feel there should be more people here," she said. "It should be a day all of us should remember."

Mandela proved an adept politican at the City Hall ceremony, praising Dinkins's election and Cuomo's oratorical skills and making a light-hearted reference to the recent marriage of Cuomo's son, Andrew, to Kerry Kennedy.

Winnie Mandela, clad in purple-and-white African garb and headdress, drew cheers when she asked the crowd to help "to launch the last onslaught on the racist Pretoria regime. Our children will remember you in the books of history." She then led the throng in a Zulu chant of "Amandla!" {power}.

After a meeting with black journalists at Gracie Mansion, the official mayoral residence, the Mandelas were joined at a private dinner by Dinkins, Jackson, Belafonte, Warner Communications chief Steven Ross, broadcast executive Percy Sutton and others for roast loin of lamb, wild rice, honey-glazed carrots and mixed fruit tarts.

Nelson Mandela retired to a queen-sized, imitation-bamboo bed that officials hoped would accommodate his 6-foot-4 frame. The move necessitated eviction of the mayor's son, David Jr.

The hectic pace is to continue Thursday with events including

an evening rally in Harlem and a concert and speech at Yankee Stadium.

Staff writers Kenneth J. Cooper, Lynne Duke and Gwen Ifill and special correspondent Laurie Goodstein contributed to this report.