Millions of Americans celebrated America's 226th birthday Thursday with parades and patriotism undeterred by possible terrorist threats.

"The anniversary of America's independence is a day for gratitude and a day of celebration," President Bush told 8,000 people in Ripley, W.Va.

"In this year — American patriotism is still a living faith — we love our country only more when she's threatened."

Remembering the Sept. 11 attacks and celebrating America's enduring strength was a theme common to many of the celebrations. In New York, the annual Macy's fireworks display was a tribute to the victims and heroes of the attacks.

Philadelphia's parade honored the first rescuer who arrived at the scene of the Flight 93 crash near Shanksville on Sept. 11 and four of the last New York City firefighters to escape the World Trade Center towers before they collapsed. A day earlier in Des Moines, a Yankee Doodle Pops concert honored the Sept. 11 heroes.

"Enjoy the fireworks, remember those that we lost, and look forward to the future, which is why they all gave their lives," New York mayor Michael Bloomberg said.

In Florida, at Disney World, 500 immigrants from 89 countries were sworn in as U.S. citizens. Another 82 became Americans in Virginia during the 40th annual Monticello Independence Day Celebration and Naturalization Ceremony.

After Sept. 11, "we began to think about being American in a way we never had before," author Frank McCourt said in Virginia.

Not everyone joined in the nationwide celebration.

"I don't think I'll ever feel completely safe again" after Sept. 11, said Sonny Palazzo, 52, of Danielson, Conn. "What's scary to me is, what's going to be next? But I can't let it ruin my life."

The U.S. government deployed combat jets over New York, Washington and other U.S. cities in an effort to ensure that Americans could safely enjoy the nation's 226th birthday.

The government kept the nation on "yellow" alert status, the middle of five levels, White House press secretary Ari Fleischer said. "There is no change in the security situation," he said. "It remains a time of celebration and vigilance."

Some Muslims around the nation plan to avoid large gatherings for fear of being mistaken for a terrorist by edgy law enforcement officers or suspicious citizens.

"As a Muslim, especially during this specific holiday, I have a concern of being racially profiled by the police and the federal agents," said Mohamed El Filali, an official with the American Muslim Union.

Sohail Mohammed, an immigration attorney from Clifton, N.J., planned to be out of the country on the Fourth of July, taking in Niagara Falls from the Canadian side of the border. "Every time there is a high alert, Muslims have to be on a higher alert for a backlash," he said.

Two senior U.S. officials, speaking Wednesday on condition of anonymity, said U.S. intelligence is picking up more talk about an attack on or about July 4, but there is still nothing specific.

Before the holiday, retailers reported brisk fireworks sales, in part because of resurgent patriotism. George Zambelli Sr., president of New Castle, Pa.-based Zambelli Fireworks, said Old Glory colors are in this year.

Celebrating the holiday is "the best way to stick it to the terrorists," Bloomberg said. "It will show them that we are not afraid and that they have not succeeded."

The Associated Press contributed to this report.