Going to take issue with the statement that there’s little use for Spanish in the Dakotas. Clearly, someone’s never been there…
Our town would probably have plenty of Hispanics no matter what, but interestingly the community dates back to the 1920’s when one of our mayors had a Mexican gardener who liked our town so much, many others from his community followed him.
Sometimes comparatively obscure languages can acquire real importance. The man who became the first Jew to get tenure at Yale college got there by being an expert in Malay and related languages of the Southwest Pacific region in 1941. Pashto speakers became celebrities in 1979 and again in 2001.
The world has plenty of Mandarin speakers who are also pretty fluent in English, but there isn’t the same kind of glut of people who can competently move between English and Uyghur or other Turkic languages of Central Asia. Or, for that matter, Turkish. And no one has mentioned Portugese or Indonesian in this thread: the mother tongues of about 250 million people each, only a tiny portion of whom have learned English. Those aren’t necessarily “most in demand” languages, but they are languages where there may be real value in knowing them.