Spanish isn’t an official language in the US. But English isn’t either.
Here’s a fun fact for you: the United States of America has no official language in its Constitution. So English, while the de facto language of the country, is not the de jure official language. So neither English nor Spanish (which has been spoken in American territory since the first European settlements were made in the region) are official languages in the United States.
However, some states have legislated which are their official languages. All states with that kind of legislation list English as an official language, while others add Native American languages. Spanish is not an official language in any of them, even though it is the second most spoken language in the country. In Colorado, Florida and the Southern United States, there are Spanish speaking communities which have existed since the 16th century.
After all, the American Southwest was once a province of Spain. Spanish was an official language in California until the 19th century, when the Spanish-speaking community was overthrown by the English speaking one. Today, most Spanish speakers come from recent immigration waves from South America.
Other states, despite not having an official language, give Spanish a special status. In New Mexico, for example, laws are usually published in both English and Spanish, particularly in local communities where Spanish is widely spoken. Texas, also on the US-Mexico border, requires state agencies to provide aid in Spanish for residents with limited English proficiency.
Spanish is, of course, one of the official languages of Puerto Rico, which is not a state but a territory of the United States. It’s the only part of the country where Spanish is the most used language in day to day activities, government and education.
Will Spanish ever become an official language in the US?
It’s also very likely that Spanish won’t ever become an official language in the US. Political facts notwithstanding - which would undoubtedly make it very hard for aspiring legislators - we need to take into consideration that the majority of Spanish speakers in the United States is also proficient in English. Younger generations and heritage speakers are increasingly English-dominant, even though many make an effort to speak Spanish as well.
Amongst Spanish speakers born abroad, it’s also fair to say that most have some sort of English proficiency. Therefore, the need to provide special assistance in Spanish will not increase, unless there is a new wave of Latin American immigrants. Some people think this is a possibility because the numbers of recent migrants from Venezuela, Honduras and Nicaragua is rising. But, if anything, new immigrants will merely maintain the levels of current Spanish usage as new generations drop it.
It’s worth noting that during their heyday, German, Polish, Italian and even Swedish were spoken by a significant number of people in the US. Germans were once the biggest ethnic group in the United States, while Italy and Poland were the biggest sources of immigrants during the first half of the 20th century. With time, all of them have faded without ever becoming official.
Of course, none of them ever had as many speakers as Spanish, which is spoken across 22 countries around the globe. But all of them eventually eroded with the generations, especially Polish which disappeared in a single generation. So far, Spanish has been more lasting, with almost half of third-generation Latin Americans still speaking it to some degree. The lost link seems to happen in the fourth generation onwards.