By Mark Egan
NEW YORK (Reuters) - The attacks of September 11, 2001 changed life in the United States forever, but 10 years after the devastating hit, New Yorkers have learned to live in a more dangerous world and are ready to move on.
Police heightened security in New York on Friday in response to a credible but unconfirmed threat of an al Qaeda plot to attack the city again on the anniversary of the downing of the World Trade Center towers by hijaked airplanes.
In Manhattan, police set up impromptu check points and searched vehicles, but New Yorkers took the security alerts in their stride as a normal part of their life.
Ahead of Sunday's commerative ceremonies at Ground Zero, there are signs that some New Yorkers are tired of it all.
Don't call it Ground Zero, don't use the term 9/11 widow and don't read the names of the dead, they say.
New York Mayor Michael Bloomberg wants people to stop calling the place where the Twin Towers once stood "Ground Zero," a term which implies violence on a nuclear scale.
Progress helps that argument. The new One World Trade Center skyscraper towers more than 80 stories above ground as it inches to its planned 1,776 foot height -- symbolic of the date of America's independence.
The memorial plaza is ready and the neighborhood has enjoyed a revival making it a trendy Manhattan place to live.
Some of those most devastated by the attacks no longer wish to be defined by it. Among them is Kristen Breitweiser, who became a widow, activist and author after her husband died when hijacked planes slammed into the World Trade Center.
"I don't identify myself as a widow anymore. I'm a single mom," Breitweiser, author of the 2006 book "Wake-Up Call: The Political Education of a 9/11 Widow," told Reuters.
Sunday's ceremony includes moments of silence marking when hijacked passenger planes hit the Twin Towers as well as when they collapsed. There will also be moments of silence marking when hijacked planes crashed into the Pentagon in Washington and a field in Shanksville, Pennsylvania.
President Barack Obama and former President George W. Bush will be among dignitaries joining victims' families to hear the reading of the names of those who died on September 11.
MORE DANGEROUS WORLD
Research shows that Americans accept a more dangerous world with plots such as the one being investigated on Friday.
Over the past decade there have been many New York plots -- some aspirational, such as one to blow up subways and another to explode a pipeline near John F. Kennedy International Airport and others more visible near-misses such as the failed car bomb attempt in Times Square in 2010.
Some 58 percent of New Yorkers and 49 percent of Americans believe "another terrorist attack in New York City, causing large numbers of lives to be lost," is likely, a new poll by Quinnipiac University revealed.
But highlighting how the expectation of attack has practically become background noise to many Americans, New York is the top U.S. domestic vacation choice, the poll revealed.
Some people such as Gennaro Esposito, a Manhattan butcher, say they are tired of ceremonies such as Sunday's.
"Every year it's the same thing. They just don't seem to let it rest," said Esposito, 47. "Let the dead rest and let it be done. They are constantly reminding us so it's hard to move on. Let the dead rest and let New Yorkers move on."
People are busy with today, not with 2001, said Judith Richman, a University of Illinois at Chicago epidemiologist who has studied the impact of September 11 on mental health.
"With the recession, unemployment, underemployment and people's fear of losing their jobs, 10 years after 9/11 will bring back a lot of memories briefly," she said. "But then, people will return to their everyday lives."
Also pushing Americans forward is the death of bin Laden, long seen as a devil for leading al Qaeda which perpetrated the attacks. After his execution by U.S. troops in a raid in Pakistan, many people displayed a visceral hatred with celebrations outside the White House and at Ground Zero.
As the Pentagon draws down troops in Iraq and Afghanistan, those wars don't dominate media coverage as much as they did.
And much has happened in the decade since the attacks, from Hurricane Katrina that devastated New Orleans to the election of America's first black president.
As the 2012 presidential campaign warms up, the economy and high unemployment are the top issues, sending the war on terror and security lower on voters' priorities.
Some argue that the weak state of the U.S. economy can be traced to the attacks of September 11, after which the United States spent trillions of dollars and lost thousands of lives on wars launched by the Bush administration.
"What 9/11 did was distract the United States significantly, causing it to put focus on things that were not in America's long-term interest," world-renowned development economist Jeffrey Sachs told Reuters. "This very militarized approach ... cost trillions of dollars and, I believe, weakened the United States."
(Additional reporting by Ellen Wulfhorst, Barbara Goldberg and Paula Rogo in New York and Leslie Wroughton in Washington, editing by Anthony Boadle)