Roughly how popular is squash in the U.S.?

Also why are there so few U.S. professional players? Is it simply not that well-known or do other sports take precedence over it? (obviously the likes of american football, baseball and such have longer standing within schools/colleges etc. as they have been around longer and are more commonly known in the same way football and rugby are in the U.K. - but is it really so far down the popularity ladder?) This is just out of interest, not meaning to be some obscure fascination...