Linguist Jack Grieve studies regional variations in languages using quantitative methods. A year ago he posted a number of maps of the United States showing regional variation in swear word usage, based on a corpus of nearly nine billion geocoded tweets. Stan Carey of the Strong Language blog has more on the maps:
Hell, damn and bitch are especially popular in the south and southeast. Douche is relatively common in northern states. Bastard is beloved in Maine and New Hampshire, and those states—together with a band across southern Arizona, New Mexico, and Texas—are the areas of particular motherfucker favour. Crap is more popular inland, fuck along the coasts. Fuckboy—a rising star—is also mainly a coastal thing, so far.
I love everything about this. See also Stan’s follow-up post from last March. (Thanks to Natalie for finding this.)