My experience talking with folks (both Caucasian and not) in the places in the USA where I've worked or lived - i.e. outside of eGullet folks - have generally indicated very few folks like (or even think of) eating or cooking lamb.** Too "gamey"/semi-nasty to them. The default remains beef/chicken, sometimes pork. But lamb - rare. Duck is more common with E/SE Asians, and turkey is beloved by many too - but beef/chicken still dominates. But of course this is old news to folks here.
** ETA: One exception might be Muslims and other folks like some South Asians, to whom sheep meat is common. Note I didn't say just "lamb", although in more recent times "lamb" (as imported from Oz and NZ) have become "fashionable". ;-) P.s.: The term "mutton" in SE Asia (and also widely in S Asia) commonly means GOAT meat, not sheep, although it can also mean sheep - one may have to ask or be aware of the usage in certain sub-cuisines or geographical areas.