Russian speakers in Florida counties, percent per population. From the MLA Language Map. Flagler County leaps out at you as a hotbed of Russian, but if you poke around in the data, you'll find that only 275 people reported Russian as their main language.
I'm sure the number is far higher, in the thousands, but that most Russians are eager to assimilate and reluctant to self-report their home language, choosing instead to self-identify as English speakers. Still, the relative numbers of self-reporting Russian speakers in Flagler is strikingly higher than in other Florida counties.