Around the world, most students study English as a foreign language. If all Americans had to study one foreign language, which one should they study. Why?

First of all, should the Americans study this language because more people speak this language. I think it is language of the age and it is characterized by the benefits. It is these benefit first, some countries speak this language and some companies also speak this language. In addition to some cities in America. I have heard from some people that say some United States cities speak Spanish.They should learn this language, I expect that the American people had no problemin learning this language, but I expect they do not have enough time to learnbecause most of them busy with his life and studies. On the other hand that the people of American owns language of the age and the language of the future, but I do not mind owning another language. I hopeto learn the Spanish language, but I will speak  Spanish language in the future.