Per the stats
@edog37 provided, 0.16% of the American population participates in hockey. What would be interesting is
how much that number goes up if you isolate the most active population equivalent. For e.g., at a glance, it appears to shoot up to 1% in Minnesota, where there's a much greater interest.......that's
still short of the 1.4% of the overall Canadian population that participates.
That said, as
@Fatass pointed out, the number of registered players as a standalone statistic doesn't prove much about the "niche"/"non niche" value of hockey as a consumer sport in either country. There are over 14 million listed soccer participants in the United States, as compared to 5.5 million that report participating in gridiron football. You're deceiving yourself if you think soccer is the less "niche" of the two.