Deciding the host city for an Olympics used to be a far simpler affair. The International Olympic Committee would gather, discuss some locations, reject Detroit (seven times!) and choose a capital/leading city from one of the usual suspects, often unanimously.
Sometimes these decisions were motivated by generosity (Antwerp got the 1920 Games in recognition of Belgium's WWI treatment), sometimes it was a case of being the next cab off the rank (Amsterdam lost to Paris in 1924 so got it in 1928) and every now and then they would give the Games to Los Angeles because nobody else wanted them (1932 and 1984).
You would occasionally get a nail-biter (Melbourne beat Buenos Aires 21-20 to get the nod for 1956) and sometimes there would be a slight hint of national prestige involved (LA v Moscow in 1976 and 1980), but generally these votes did not bring nations to a halt, signify historic shifts in global influence or upset anybody, apart from perhaps Detroiters.
That has all changed now, though.
Whichever of Chicago, Madrid, Rio de Janeiro and Tokyo gets the 2016 Games will have come through perhaps the closest bidding race in IOC history.
For the winners there will be initial euphoria, the gradual realisation of the hard slog ahead and the carrot of throwing the world's greatest party. For the losers there will be instant dismay, drawn-out recriminations and the gloomy prospect of P45s.
So who's going to win then?
Let's get this out of the way early on: I don't know.
And neither do any of the journalists, bid insiders and assorted IOC watchers I have spoken to in the last few months. It's a hoary old cliché but that doesn't make it any less true, this race is too close to call.
The last ranking we've had from the IOC came in March 2008 when it released its evaluation reports on all seven candidate cities (the shortlisted four plus Baku, Doha and Prague). This was a technical assessment of how each bid measured up on things like government backing, transport and security.
On this more black and white judgement, Tokyo scored marginally higher than Madrid. Then there was a gap to Chicago, with Rio back in fifth, behind Doha.
The IOC's decision to shortlist Rio over Qatar's capital brought considerable criticism from the Arab world but Doha's proposition fell down in a couple of areas (the most significant being an autumn scheduling to avoid the summer heat and Doha's relatively small population...not good for ticket sales), while Rio offered a tantalising opportunity to tick off another continent and the potential for the mother of all carnivals.
Those two factors remain Rio's strongest cards and many pundits are starting to wonder if they could be enough for a winning hand.
That would be some comeback but deciding which city gets the Games has always been about more than who has the best transport plan - geopolitics, wow factor, commercial interests, what the big broadcasters want (and for "big" read American) and the private whims of the IOC's cosmopolitan membership all play their parts.
Which is why the latest odds from British bookmakers fly in the face of those early IOC reports: Chicago are odds-on favourites, with Rio second, Tokyo not far behind and Madrid adrift but not out of it. That order hasn't changed over the last six months but the Windy City's odds have stiffened, while the others' have drifted.
Chicago's frontrunner status is supported by the findings of Around the Rings, a respected newsletter and website that has been covering Olympic news for 20 years.
The most recent "ATR 2016 Olympic Bid Power Index" has America's third largest city on 80 points out of 110 (ATR looks at the IOC's 11 key criteria but incorporates more subjective elements too), Madrid second on 78 and Rio and Tokyo joint third on 77.
So when the IOC's 106 members gather in Copenhagen to vote on 2 October, Chicago has a good chance of becoming the fourth US city to stage a summer Games - 112 years after it won the right to host one only to have St Louis pinch it - but that is all it is.
Londoners celebrate the news from Singapore in Trafalgar Square four years ago
If we compare this race with the one that came to such a thrilling conclusion in Singapore four years ago, this year's London and Paris appear to be Chicago and Rio. But unlike 2005, the 2009 race has no rank outsiders.
While there are only three points separating first and last in ATR's latest rankings, there was a 20-point spread in 2005. New York and Moscow were perceived to have fought lacklustre campaigns and that was soon borne out by the voting.
Ed Hula, ATR's editor and founder, believes this year's race is so close it's "scary".
He believes there could be just a few votes between all four cities in the first round of voting and whoever loses will do so knowing they have put together a plan that would measure up against plenty of previous hosts.
Who their first-round backers transfer their votes to in the subsequent rounds will settle who gets the 2016 Games and that is when you get really lost in the possible permutations.
"I go back and forth between Chicago and Rio - Chicago's got the hotel rooms but Rio has that emotional pull," said Hula.
If that assessment leaves Madrid and Tokyo feeling a little bit glum, they shouldn't throw in the towel just yet.
The Spanish capital, an unlucky loser in 2005, has plenty going for it this time too: a sound plan, most of its venues built, the behind-the-scenes support of former IOC president and current honorary president Juan Antonio Samaranch and credit in the bank from previous bids.
On the debit side, however, is its location, which is something it can do nothing about. A win for Madrid in Copenhagen would make it three Olympics in a row in Europe (London 2012 and Sochi 2014).
It is a similar story for Tokyo. A compelling case on paper (a compact Games with superb green and redevelopment credentials), the world's largest metropolitan area might be marked down for being too like and too close to Beijing, last year's host.
But the Japanese can take heart from another important indicator of bid success - GamesBids.com's BidIndex. This mathematical model takes the kind of things the ATR index measures and combines them with a statistical analysis of historic voting patterns.
It's all totally beyond my limited maths but it comes up with a journalist-friendly number: Tokyo currently leads with 61.41, Rio is second with 59.95, Madrid third on 58.73 and Chicago last on 58.37. The first three all saw their scores rise slightly over the previous six months, while Chicago's fell.
But again, the closeness of this race is readily apparent, just three points between the four cities. There were 17 points between top-ranked Paris and bottom-ranked Moscow going into Singapore.
US President Barack Obama has close ties with Chicago
"Nobody can be written off and I don't think that's happened for a Summer Games for a long time - it's a real puzzle," said GamesBids.com's Robert Livingstone.
We might get a few more clues to the puzzle on Wednesday, when the IOC's evaluation commission (a 13-strong team set up in the wake of the Salt Lake Games bribes-for-votes scandal) publishes its final report, but my guess is that we'll be left with the same equation: the IOC's heart calling for Copacabana but its head worrying about crime and passing up the riches on offer in Chicago, a confusion that might just let in Madrid or Tokyo.
Could that decision be made a little bit easier by the presence in Copenhagen of the world's most powerful man? Can Barack Obama, Chicago's top trump, risk so much political capital on anything other than a slam dunk? Can he risk not going? Is it fair the US gets a Summer Games every 20 years when there are continents still waiting for their first? Will Detroit ever bid again?
Like I said, I don't know...but I'm looking forward to finding out. And if there are any fresh pointers in those final reports I'll post a comment below.
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