...why not football mom, baseball mom, or basketball mom?
Soccer mom, as far as I can tell, is an American term made popular during the 1996 presidential elections, used to describe a key demographic - mothers who, by spending lots of time shuttling their children to and from soccer practice, demonstrate that they were concerned about their children. Other attributes often associated with this demographic are suburban, married, busy, drives a minivan/SUV and so on.
What puzzles me is the choice of sport in the term: why soccer? Globally, soccer is an extremely popular sport, but there are many sports more popular than it in USA, and I imagine this would extend to after-school activities. I see that in Canada there's the equivalent term hockey mom which makes more sense.
Was the term coined in a place and time where soccer was a more natural choice? Is soccer a more prominent sport in the after-school world? Or was there some other historical accident?