New Yorkers delivered expected but much-needed victories to senators Clinton and McCain yesterday, as Democrats offered a home-state boost to Mrs. Clinton and Republicans guaranteed a trove of delegates to Mr. McCain.

Mrs. Clinton secured a clear win over Senator Obama in a result that was called by television networks immediately after the polls closed at 9 p.m., prompting a roar from the hundreds gathered at her election night party on the West Side of Manhattan. With 99% of precincts reporting, the New York senator led with 57% of the vote to 40% for Mr. Obama. More than 1.7 million Democrats turned out across the state — more than twice as many as turned out in 2004 — with Mrs. Clinton receiving more than 1 million votes.

The results quieted fears among Clinton supporters that the Illinois senator would cut into an Empire State lead that once seemed insurmountable. Mrs. Clinton also held the city, fending off a late effort by the Obama campaign. The closest borough was Brooklyn, where Mrs. Clinton clung to a 49%–48% lead.

“Tonight we are hearing the voices of people across America, people of all ages, of all colors, all faiths, and all walks of life,” Mrs. Clinton told her cheering supporters in a ballroom at the Manhattan Center Studios. Appearing minutes before the California polls closed at 11 p.m. Eastern time, she thanked voters in each of the states she won last night, culminating with “the great state of New York.”

Leading Democrats from across the state were in attendance, including Governor Spitzer, the speaker of the City Council, Christine Quinn, and Reps. Joseph Crowley, Jerrold Nadler, and Anthony Weiner. The victory will give Mrs. Clinton a majority of the 232 proportionally allocated delegates at stake yesterday in New York.

For Mr. McCain, the victory over Mitt Romney is perhaps more significant. Unlike for Democrats, New York is winner take all for Republicans, meaning Mr. McCain will take 101 delegates to the party’s nominating convention this summer. The Arizona senator emerged as the front-runner in New York after his victory in South Carolina last month, but he was helped by the endorsement of Mayor Giuliani and most of the state’s Republican leaders in recent weeks. With 98% of precincts reporting, Mr. McCain had 51% of the vote, Mr. Romney had 28%, and Michael Huckabee had 11%.

Across the five boroughs yesterday, New Yorkers added their voice to the battle that has been brewing for more than a year between their home state senator and Mr. Obama.

In interviews at polling places in Manhattan and Brooklyn, voters cited many of the same concerns expressed by those who preceded them to the polls in Iowa, New Hampshire, South Carolina, and the other early primary states. Several Obama supporters said they were won over by his calls for change, while other voters said they were swayed — for better or worse — by Mrs. Clinton’s eight years in the White House as first lady.

“I voted for him because I really saw that he has a fresh, different look for the direction the country needs to be going in,” an Upper West Side resident who works as a research librarian at the Frick Museum, Rodica Krauss, said of her support for Mr. Obama. Ms. Krauss, 57, said she switched her registration from Republican to vote for him. Mrs. Clinton, she said, has “been an insider for a long time. Somehow she will follow the same direction.”

David Motson, a librarian at Columbia University, said he voted for Mrs. Clinton, citing her experience.

“She will have less of a learning curve,” Mr. Motson, 44, said after casting his vote at the Margaret Douglas School on West 122nd Street. “She had to get something out of living in the White House and being married to a president for eight years.”

A Brooklyn Heights resident, Gery Diamond, said she switched her support to Mr. Obama in the last two weeks. “I wanted to vote for Hillary,” she said. “I liked her before her campaign tactics in South Carolina when she said false things about Obama. I was let down by the Clintons and how he campaigned with such vitriol. It tilted me.”

Giovanni Vitacolonna, 59, circulation supervisor for a magazine in Manhattan, said he supported John Edwards before he dropped out of the race last week.

“I voted for Obama because I don’t want to do Billary again,” Mr. Vitacolonna said, referring to President Clinton’s influence in his wife’s campaign. “If she did it on her own I might be a little more comfortable.”

On the Republican side, Mr. McCain entered as the heavy favorite both nationally and in New York, where he has drawn the support of most party leaders.

He began his Super Tuesday bright and early yesterday, predicting victory before a crowd of supporters at Rockefeller Center.

“We’re going to win today, and we’re going to win the nomination, and we’re going to win the presidency,” the Republican front-runner said, standing alongside his former rival, Mr. Giuliani, and a host of other state supporters at 7:30 a.m.

Mr. McCain spoke for about 10 minutes before heading across the country for a get-out-the-vote rally in San Diego. He finished the night in his home state of Arizona, addressing supporters in Phoenix shortly after 11:30 p.m.

Mr. Giuliani, a one-time front-runner, had hoped to be in Mr. McCain’s place yesterday. But he appeared in good spirits, taking the stage and grabbing an “Irish for McCain” sign from a supporter. “Welcome to the St. Patrick’s Day Parade!” Mr. Giuliani quipped, drawing laughs from the crowd. “Irish for McCain, all New Yorkers for McCain!”

Among Democrats, Mrs. Clinton has long been heavily favored to win her home state, but the Obama campaign refused to cede New York entirely and tried in particular to make inroads in the city. Democratic Party rules allocate delegates proportionally by congressional district, meaning that even if Mr. Obama lost the popular vote statewide, he could still hope to prevent Mrs. Clinton from sweeping New York’s triple-digit delegate trove.

A top New York fund-raiser for Mr. Obama, Gordon Davis, sent an e-mail to potential donors on Friday seeking last-minute contributions to fund Election Day activities. The e-mail said the campaign had targeted five districts in the city where it hoped to “steal a lot of delegates from Hillary.” Those districts comprised much of Manhattan, including Harlem, and parts of Brooklyn.

The Obama campaign was out in force in many of those areas, and in some cases with more visibility than the Clinton campaign.

In Harlem, Morningside Heights, and the Upper West Side yesterday morning, volunteers for Mr. Obama manned street corners, passing out fliers to voters on their way into the polls.

On a day when a presidential election and a Super Bowl parade competed for attention in the city, some New Yorkers turned to multi-tasking. On a downtown A train yesterday morning, four teenagers decked out in Giants jerseys and face paint traversed a subway car, asking riders if they had voted and urging them to pull the lever for Mr. Obama.

The Obama campaign said it had heard of numerous reports of problems at polling places in Brooklyn, including malfunctioning machines and complaints from voters who said their names were not on the rolls even though they had voted in the same precinct for many years. The Clinton campaign reported no such issues of its own. A spokeswoman for the Brooklyn Board of Elections, Valerie Vasquez, said officials had heard “some isolated reports” of malfunctioning voting machines from throughout the five boroughs and had determined that most were the result of voter or poll worker error. She said reports of voters being turned away would have to be investigated.