Were the initial Spanish-speaking settler communities in California, Texas, and the Southwest completely absorbed into Anglo-American society or did any of them keep their language traditions through the 20th century?
In southeastern Louisiana live the Isleños—a particular subcategory of Louisiana Creoles, descendants of Canary Islanders who settled in the state in the colonial period. I don't know enough about them to do them justice, but you should look them up. They do still speak a colonial variant of the Spanish language, although it is much more endangered than is Louisiana French. Throughout the 20th century, though, it was certainly more extant than it is today.