It doesn't compete with the big four sports but does have a significant following and financial support. After previous failures to establish professional football in North America, the MLS was launched on the back of the 1994 World Cup and kicked off in 1996 with 10 teams. Next year, the league will welcome its 20th team.
Rugby is close to being about as well established in the US as football was in 1994. If Fifa were bold enough, why not the IRB?
America have a new generation of young players. They have fledgling, semi-professional college leagues and it won't be long before they have a serious, professional league.
The infrastructure is incredible. The venues for a rugby World Cup could be incredible - there are so many to choose from. And what better way to sell the sport to the American public than seven weeks of non-stop physical carnage?
Americans have an appetite for contact sport and having the World Cup in the US could be the smartest thing the IRB ever does.
The danger for the US game is that the instant the All Blacks leave, their 15 minutes of fame is over. What next? Will any other major nation do what the All Blacks have?
The risk for other countries is that they don't have the marketing power of the All Blacks. While 61,000 fans will be at Soldier Field this morning, it's by no means guaranteed 61,000 people would be prepared to watch the US play South Africa or England.
Some English Premiership clubs have looked at playing in the US but it's hard to see, if they ever do, what legacy impact that will have.
There's no question it would be risky to give the US World Cup hosting rights, but the IRB know they are going to make record profits next year in England.
The early interest in tickets has been overwhelming and that's with most games being played in huge stadiums. Japan in 2019 is a bit of the unknown and the IRB may feel, having given the hosting rights to one emerging nation, they can't do it again with the next tournament.
But that would be short-sighted as, frankly, giving it to Ireland, Italy or Australia would be equally fraught with risk and France hosted as recently as 2007.
The only compelling alternative to the US is South Africa, which is overdue, having not been hosts since 1995.