The United States on the national level has no single official language. However, 28 of the states explicitly name English their official language. One state, Hawaii, names Hawaiian as its other official language, New Mexico gives special status to Spanish; and Louisiana the same to French. Every one of the states has linguistic minorities residing. Five states are de facto bilingual.
For 43 of the 50 states, the seond prevalent language is Spanish. See this Wikipedia article.
However, in seven states the second most prevalent language is not. It's French in Louisiana, Vermont, Maine, and New Hampshire. It is German in North and South Dakota. And it is Tagalog in Hawaii. And there's a lot of languages spoken by small numbers of people.
We have a few minority languages in the United States that are steadily decreasing in the number of speakers, so that they are in danger of becoming extinct. When this takes place, is some of our national patrimony lost? Some would argue that it is; that these languages should smehow be preserved. We don't have that problem with Acadian French in Louisiana, but Louisiana Creole does seem to be declining in number of speakers, especially in New Orleans.
We have something of a schizophrenic attitude collectively when it comes to languages other than English. On one level, most prep high schools encourage at least two years of foreign language study, primarily one of the Western European languages (Spanish, German, French, and sometimes Italian). Very few schools offer Chinese, Japanese, Russian, or Arabic, despite their increasing importance in foreign relations. And there's the classical languages: Latin and Greek. Yet most graduate programs have dropped reading knowledge in a foreign language as part of their degree requirements. (A little degree requirement slippage.)
As for everyday speaking, there are some militants that go with the stance, "Dammit, they're in the U.S. of A. By God, they ought to speak English!" As if it is any business if I address someone who is knowledgeable of French or Louisiana Creole in the tongue that they understand. We must remember that the United States when being formed was not an empty space: it already had people residing in some states that were speaking French, Spanish, Native American languages, Aleut, Tinglit, Hawaiian, and even Dutch. This is a carryover of the historical perspective that American history happened with the 13 colonies, and the other states served as bit players, except during the Great Unpleasantness (1861-1865).
[Just as a prank, I would like to hack some telephone automated answering sequence and change it to: "Press one if you want it in Louisiana Creole, two if you want it in French, three if you want it in English, and Four if you want it in Spanish." That would twist the FOXsters panties into a knot!]
Whatever, there are a lot of people that speak a language in addition to English. And whatever you do, don't treat them like they are cute dogs that have an interesting trick.
"......You speak Aleut? How cool. Say something clever in Aleut." Sometimes language can be entertaining, though. California, with English as its official language, has a locally-derived language, Boontling.It's spoken around Boonville by some, primarily as a novelty.
Having squawked enough, I'll end with a prayer in Louisiana French Creole:
Nouzòt Popá, ki dan syèl-la Tokin nom, li sinkifyè, N'ap spéré pou to rwayomm arivé, é n'a fé ça t'olé dan syèl ; paréy si la tèr Donné-nou jordi dipin tou yé jou, é pardon nouzòt péshé paréy nou pardon lê moun ki fé nouzòt sikombé tentasyon-la, Mé délivré nou depi mal. Amen.