The United States Census Bureau just released their annual report on languages spoken in the United States, and it contains a whole of information.
Here are three accessible summaries:
Multicultural California leads nation in linguistic complexity is from The Sacramento Bee.
At Least 350 Languages Spoken In U.S. Homes: New Report is from NBC News.
Here’s an excerpt from the last link:
You might also be interested in The Best Resources For Learning The Advantages To Being Bilingual.