NEW YORK -- In the months after nearly 2,800 people died in the terrorist attack that destroyed the World Trade Center, the Bush administration pledged $21.4 billion to address the emergency. The extraordinary allocation of federal disaster relief, while less than local elected officials had petitioned for, was meant to reassure, restore and restart an emotionally and economically ravaged New York City and its surrounding region.

More than 15 months later, some $4.5 billion to $5 billion has made its way from Washington to New York. Significant sums of money were made available almost immediately, and they made possible early progress in providing for victims and establishing a sense that the city could rebound.

About $600 million was sent to cover the costs of the monumental task of cleaning up the site. An additional $401 million has been distributed to 10,000 downtown businesses to keep them afloat. And $493 million in tax-free bonds has been approved to help finance major construction projects, including three residential complexes around Ground Zero.

But many victims, elected officials, business executives and others are both confused and angry about why, more than a year after the most serious terrorist attack on American soil, less than a quarter of the federal government's promised financial assistance has been realized. The explanations, based on an examination of financial filings and interviews with government officials, real estate experts, watchdog organizations and downtown residents and business people, are varied.

Some $1 billion of the $21.4 billion in aid, it turns out, will buy insurance for the companies that conducted the cleanup, which they would use to defend themselves against any lawsuits. Aides to some New York elected officials who have tracked the money also believe that some of New York's promised millions has gone to victims and institutions in Pennsylvania and Washington, the other two sites of devastation wrought by terrorists on Sept. 11.

Moreover, federal officials did not intend to deliver another huge chunk of the money -- some $5 billion to rebuild the transportation network downtown -- for years, determined to wait until there was a fully formulated plan. No one doubts that the government will make good on its pledge. But the jobs that such a project would bring and the tangible benefits to the city remain far off.

Further, many businesses and residents were shocked to learn that hundreds of millions of dollars in grants available to them were subject to federal taxes, a fact that both reduced the real value of that aid and discouraged some from taking advantage of it.

Many people have also failed to realize that about a quarter of the total aid package -- some $5.5 billion -- was made up of tax breaks, not real dollars. So the ultimate value of that portion is the subject of great debate, with some economists and real estate experts in the city worried that it is largely an illusion.

Distrust among the government agencies involved in controlling the aid, and self-confessed bureaucratic missteps by the Federal Emergency Management Agency, which is in charge of channeling nearly $9 billion to New York, has also led to delays in payments and disillusionment among potential recipients.

And finally, some of the money has not made its way to New York because local and state officials have not figured out exactly how to take advantage of all the available types of aid. Other bids for financing certain projects -- $90 million to help assess the long-term health of thousands of trade center rescue workers, $980 million to reimburse the city and state for the cost of deploying its uniformed forces and future fire department training, have been stalled.

"You can look at the trees, and see many things that should have been done better or quicker," said Sen. Charles E. Schumer, a New York Democrat who has been involved in negotiating the aid packages. "But if you look at the forest, it's a large and unprecedented sum of money that's basically being used in the way that it was needed and intended."

Determining precisely how much money has reached New York and been distributed is difficult. An examination by The New York Times of the dozens of sources and uses of the promised $21.4 billion in disaster aid found significant disparities in accounting for the money, both among the federal officials handling it and among the organizations and people in New York and the region receiving it.

Responsibility for definitively tracking where it has all gone remains unclear. For instance, last September, an official with the federal General Accounting Office told New York officials that the Office of Management and Budget appeared to be so uncertain of how much had been spent that it asked the General Accounting Office for an answer -- an unusual request since it is the OMB's job to monitor federal expenditures.