Soccer is the most popular sport in the world, almost everywhere but the United States.
When I grew up, I was one of the first generations of kids to play soccer. None of our parents knew the rules. Now, as an adult, both my children have played soccer and I've been able to provide meaningful guidance to them in doing so, perhaps not at international standard, but I know the game. Of course, my son now plays lacrosse, I game I'd never even seen played until my late 30s, and still don't really understand, so the cycle repeats itself - although lacrosse is a Pre-Columbian American sport from the Northeast, even if it didn't reach its modern form until much later.
Pro and college American football is still the king of American sports, but fewer and fewer school kids play it, in part, because the risk of injury is so high relative to soccer, basketball, and other leading sports. Rural school districts that once prided themselves on their football prowess now field reduced size teams if they have football teams at all.
I played T-ball (I was so bad that I struck out once, which is bad when the ball is sitting still on a stick) and played on a firm softball team once, but never advanced to fast pitch. Baseball is hardly played at the school level anymore, in part because it is a summer sport when school is out of session. Also, to be honest, baseball is boring as sin and lots of people don't watch it or have an interest in playing it anymore. A perfect game is my idea of a nightmare. We see about one Rockies game a year in person for the stadium experience. No sport is easier to follow in a radio broadcast or with a newspaper box score report. And, we watched when the Rockies made it to the World Series, but I don't even understand the playoff system in baseball and they play so many, many games. I also don't get why the World Series includes only the U.S. and Canada, despite the fact that there is one more great baseball playing country in the world, Japan, that is excluded from it.
When I was growing up and first playing soccer, the U.S. was awful at the sport and didn't have a pro-soccer league. Now, the U.S. has a pro-soccer league (including Denver's own Colorado Rapids franchise with its own dedicated soccer stadium at Dick's Field), and we have made it to the final 16 in the FIFA World Cup in Brazil (an even that occurs only every four years, like the Olympics).
Symbolically, the new found American love of soccer, demonstrates that even the U.S. is slowly making its way towards the international norm. It has been slow in coming, just as we have been reluctant to adopt international norms like the metric system in our daily lives, universal health care, belief in evolution rather than creationism, to disavow life without parole sentences for juveniles, to abandon the death penalty, and to cease using of jury trials on a widespread basis to resolve civil disputes. It is a sign of cosmopolitan times.