When we first moved to San Diego my parents were in property management at an upscale complex near the beach. We had two residents that were in professional sports - one was on the San Diego Chargers - the other was on the San Diego Sockers. Can you guess which guy got mobbed by the kids more? And he wasn't even a popular player - they just knew he was on the team.
Soccer in the US is great for kids - maybe up through high school and a little college (I hear the scholarships for this are great for girls - but my daughter lost interest at 10, about the time she started playing catcher in fast pitch softball - now THERE'S a sport!). However, beyond that it's just never really taken the nation "by storm" like football, baseball - and hell, I'm shocked - even NASCAR has reached beyond its redneck roots in the past few years.
There was that bit of time when Mia Hamm got all the girls wanting to play soccer... and I remember the Pele games on Atari back in the day... but America has had a "fleeting" romance with soccer over the years and that's about it...