Uh, family back home?  Friends?  I have a cousin brought here back in the 1960's from Slovakia.  She still has a thick accent (which sounds lovely, btw), because she still keeps in touch with family back there and visits often.

I find it arrogant and stupid how Americans poke at a foreigner's accent in English.  Uh, that person knows at least two languages.  How many do typical Americans fluently speak in?  Usually barely their own native tongue, and many are too stubborn to learn a 2nd.