To be in Washington, DC, at the turn of the new millennium was to witness a nation at the height of its unrivalled and unipolar powers.
In the run-up to the new year celebrations, US publishers rushed out a welter of self-congratulatory books on what had come to be known as the American Century.
In the same spirit, the White House Millennium Council selected items for a time capsule that included a fragment of the dismantled Berlin Wall, footage of Neil Armstrong's moon walk and Louis Armstrong's trumpet, relics that captured for posterity America's military, technological and cultural hegemony.
On the National Mall, the Clinton administration staged a lavish celebration entitled America's Millennium, seemingly untroubled by the niggardly fact that the US had not made much of an impact for 776 of the past 1000 years.
As the countdown started, fireworks skipped purposefully across the Lincoln Memorial Reflecting Pool and then ignited the base of the Washington Monument.
When fully illuminated, the obelisk looked like a giant, national exclamation mark, or even an imperial erection. The message was emphatic: America is No 1.
Just 21 months later, after American confidence had already been dented by the dotcom bust and the constitutional convulsions of the Florida election recount, its vulnerabilities were much more horrifically exposed by the attacks of 9/11. Not long after, commentators and historians cast their eyes over the ruins of ground zero and saw in them the seeds of American decline.
Thereafter, the self-inflicted wounds of Iraq, a stubborn insurgency in Afghanistan, and a hunt for Osama bin Laden that seemed for years to be going nowhere all reinforced the declinist view.
In global diplomacy, the US no longer spoke with a clarion voice, while the detention centre at Guantanamo drastically undercut its moral authority and its claim to be the foremost protector and sponsor of freedom.
Worse was to come with the collapse of a bank in September 2008 that arguably sent more powerful shock waves through the US than the disintegration of the twin towers: the subprime mortgage crisis; the near evisceration of Wall Street; a much-quoted report from Goldman Sachs predicting that China would become the world's largest economy by 2027.
Again, they reinforced the increasingly widely held view that the US was on the nose. And even though the election of Barack Obama offered compelling proof of the country's capacity for renewal and reinvigoration, the headline in satirical newspaper The Onion hinted at the country's underlying state of mind: "Black Man Given Nation's Worst Job".
There is no denying that the US has had a terrible decade; its worst since the decade between 1965 and 1975, which covered Vietnam, the urban riots, the assassinations of Martin Luther King and Robert Kennedy, and Watergate.
But are the declinists overstating their case, and can the US be so easily written off?
Though not a country usually associated with self-doubt, it is worth remembering that declinism has been a common thread through US history, whether it was post-Sputnik, post-Vietnam, post-Watergate or post-Tehran.
Gore Vidal was even more precise when he identified September 16, 1985, as the date of the fall of the American empire: the day the Commerce Department announced the US had become a debtor nation.
Each time, of course, the US rebounded (although Vidal was definitely on to something). It is for good reason that America's great national laureate is Mark Twain, who warned of the perils of rashly composed obituaries.
Notions of American decline have been amplified, of course, by the rise of the rest.
And, unquestionably, China poses a more serious long-term threat to the US than the Soviet Union, which did not possess a durable economic model, or Japan, which did not have a big enough population.
Still, by the time the US approaches the emotional landmark of the 50th anniversary of 9/11 my hunch is that it will still hold global sway as the pre-eminent economic, military, diplomatic, technological and cultural power.
An Anglo-centric world will continue to look to Silicon Valley for its hi-tech innovations, Wall Street for finance, Harvard, Massachusetts Institute Technology and Yale for the gold standard in higher education and research, Hollywood for its movies, the likes of Facebook, Google and Twitter for its online smarts, HBO and AMC for the best in television, Houston and Cape Canaveral for galactic exploration, US research labs for the latest in biotechnology and nanotechnology, its great medical campuses in Boston, Chicago and Baltimore for disease breakthroughs, Apple for its gadgetry, and the US military and its American suppliers for the most up-to-date weaponry. Amid all the present gloom, perhaps the chief cause for optimism is that the US is continuing to attract waves of hopeful new immigrants and many of the finest undergraduate and postgraduate brains. Three-quarters of the PhDs awarded in US universities now go to foreign students, a statistic cited as evidence of its decline.
Crucially, however, two-thirds of these foreign PhDs stay for at least five years after graduation, thus carrying on the brain gain. Tellingly, this is true for nine out of 10 Chinese doctoral students, the highest proportion of any foreign nation.
For sure, America faces problems aplenty, not least the gargantuan scale of its debt - the genuine "Red Menace" - and the impoverishment of US politics.
Washington has almost reached the point of ungovernability, given the need for super-majorities in the Senate and the extreme partisanship on daily display in the House of Representatives.
Not even electoral mandates seem to carry much sway in these hyper-aggressive times and the very legitimacy of the past three presidents - Bill Clinton, George W. Bush and Obama - has been contested. No wonder Rahm Emanuel, Obama's former chief of staff, took to calling Washington "F . . knutsville", then got the hell out. When the rough-and-tumble politics of Chicago offers something of a safe haven, there is surely something seriously amiss.
So, what of the lasting effect of 9/11? Again, my sense is that it is easily exaggerated.
When in late 2003 I left my posting in Washington to cover the Bush administration's war on terror in Afghanistan and Pakistan, I filed my wistful "how America has been transformed" farewell dispatches and pretty much followed the well-trod analytical path that the county that had been overtaken in an instant by massive and irreversible change. Reshaped and distorted forever, from the erosion of civil liberties to the delays and irritations at airports, from the pervasive sense of gloom that America's best days were yesterdays, and the fear that hope would never fully reassert itself.
On trips back to the States, however, I am constantly struck by how little it has changed. For a long time, one of the central tenets of post-9/11 "new normalcy" theory was that Washington and New York would come under intermittent, possibly even regular, attack. So, too, cities such as Los Angeles and Chicago.
They would be targeted with an ever more sophisticated menu of terrorist weaponry and suffer even greater loss of life. At the very least, the detonation of a dirty bomb, packed with radioactive material, seemed impending.
However, for all the warnings about a home-grown terror threat and the potential disloyalty of young male American Muslims, there has been no American jihad. If anything, the US has come to be seen as a model of assimilation that Britain and other countries have sought to copy.
So, quick though we were to plumb the darker recesses of our imaginations, and to talk in apocalyptic terms, the new normalcy was nowhere as bad as many forewarned.
Nor, I would suggest, is America's long-term decline.
For sure, the country has had a decade it would rather forget and prefer not to have lived through, but it is worth remembering that a good many of us expected it to be immeasurably worse.
Again, the Washington Monument has its metaphoric uses. While it may have been cracked in the recent earthquake that hit the capital, still it is standing proud.