The Modern Language Association has all kinds of awesome language-related data available that you can customize depending on your interests. Most basically, you can get an interactive map showing the percent or number of speakers of various languages spoken at home by county (or number by zip code). Here is English:
Notice that the scale of the maps changes, so the same color doesn’t indicate the same percent of speakers for each language. For some languages the darkest red only indicates 1 or 2 percent.
There was one odd category I noticed. This is the map for “African languages”:
I can understand why you might lump some languages from an area together if they are so rare in the U.S. that they’d barely show up. But what, exactly, is an “African” language? It doesn’t appear to include Arabic, though it is spoken in much of northern Africa. Many people in Africa speak European languages (particularly French and English) due to colonialism. Presumably this category includes “native,” non-Arabic languages. It’s a strange category.
For those of you wondering about the little pockets of African language speakers in, say, Iowa and Nebraska, I could be wrong, but I would suspect in some of those counties it might have something to do with slaughterhouses. In the last decade or so some packing houses have recruited African immigrants, particularly Somalis, to move to rural areas and work in the plants. Again, that’s just a guess, but some of the locations fit.
UPDATE: Commenter mordant.espier says,
I think you’re wrong about African languages and meatpacking in the midwest. I know that Omaha has a significant Sudanese community, about 7,000, many of whom are refugees and asylum seekers. In Minneapolis, there are a number of Somali. They are there because of the US government, and even more because religious and charitable organizations, especially the Episcopal Church and Catholic Charities, have provided support through all stages of the immigration process. The existance of a group of refugees who are able to enlist the support of locals has created such pockets.
Anyway, moving on.You can also get side-by-side comparisons of two states. This shows the percentage of the population speaking Arabic in California and Michigan:
Number and percent of speakers of various languages:
You can compare the number of speakers in 2000 and 2005:
If you go to “Language by State” in that last link and select a language, you can then look at “ability to speak English”. Annoyingly, it only shows raw numbers, not percentages, so you have to do the calculations yourself. But here’s the breakdown for German in Michigan; clearly the vast majority of people who speak German also say they speak English “very well”:
You can also get an age breakdown (again, just raw numbers) for each language, by state. Here’s a partial list for Chinese:
I’m warning you now, the site can turn into an enormous time-suck. You think you’ll just look up the state you live in, say, and then you get started comparing things, and the next thing you know, it’s a half hour later.
UPDATE 2: Commenters have also pointed out that a) “Chinese” is as much of a thrown-together category as “African” (does it mean Cantonese? Mandarin?) and b) the site doesn’t have any information about use of American Sign Language, both great points.