Choices are:
Coca-Cola
Bourbon
Beer
Perrier
Coffee
Perrier?
In what sense?
Most well-known uniquely American beverage: Coca-cola.
Legendary American booze: Bourbon whiskey, for sure. It’s the drink of choice in all those Westerns, regardless of where they’re made.
Beer and coffee are pretty common elsewhere, and aren’t all that different from what we have here.
Well, let’s see…
Beer wasn’t invented here, and there are plenty of places in this country where you can’t even buy it, so it’s out.
Coffee… didn’t realize we had a monopoly on that. Besides, most coffee is grown outside our borders (Hawaiian kona coffee excluded) so I don’t think we can claim that either.
Perrier is French, so that’s definitely not it.
So, we’re left with Coke and bourbon. Being from Kentucky, I’m biased toward bourbon, but since they both go well together, let’s call it a draw.
Coca-Cola, hands down.
Coke. None of the others, sans bourbon, is particularly American and it has nowhere near the international presence that Coca-Cola does.
American beer is known worldwide as being crap, so that’s out…
Coke definitely.
Root beer. Only Americans will drink it.
Who says a beverage has to be invented in a country in order to qualify it to be the nation’s beverage? If that were the case, then you’d have to say that tea could never have been the national beverage of Britain.
But my vote is for Coke anyway. It’s a great drink, and there’s tons of fat Americans who drink a gallon of it a day. Excess is very American.
I would say Coke, too, but then, I hate Coke. Does that mean there’s a small cell in Guantanamo with my name on it? :eek:
On second thought, I vote Bourbon. 
I’ll second the root beer for the exact same reason. I’d probably put bourbon up there too, but not everyone can drink it.
And hey, no need for digs at fat American people. It’s not like it’s news to us.
No Coke, Pepsi!!!
It SHOULD be root beer.
But it IS Coca-Cola. I don’t think there can be any doubt.
Cheeseburger.
As a limey I’d vote for Coffee as the “yank beverage”.
Those bloody starbucks etc have effectively colonised the globe (they’re ubiquitous here, and all over Europe). I always associate coffee with Americans as you drink SO MUCH of it.
Also - it would appear that you have no idea what “beer” actually is. It’s a flavoursome alcoholic beverage - not a yellow fizzy soft drink 
On behalf of many, but not all Americans, please accept my apologies. I’m sorry about McDonald’s too. While we occasionally get to vote about our government, we have no control over corporations.
It’s Coke, whether we like it or not.
Yes, you do. It’s called not shopping there. And, much like voting, if you don’t agree with the masses, you just have to deal. As an employee of the Ubiquitous Corporate Monster, I have no apologies to offer or complaints. My stock options are through the roof and my 401(k) is healthy. Keep drinking coffee, peeps.
My vote, by sheer consumption, would be for coffee or soft drinks. It’s a tie.
I’d have to say Coke. It is America to so many people. Hell, McDonald’s probably counts selling it as 25% or more of their profits.
Coffee, the worldwide sprawl of Starbucks notwithstanding, isn’t really that ubiquitous. It has been around for a long time, and probably by volume isn’t much more common now than it was. The amount of money spent on it has skyrocketed due to designer coffee houses and the diminishing of the Folgers of the world. However, lots of other places love the stuff too. And, there’s a huge percentage of the population that thinks the shit taste like holy hell.
Coke is far more universal.