After the incorporation of these states to the United States in the first half of the 19th century, the Spanish language was later reinforced in the country by the acquisition of Puerto Rico in 1898. Later waves of emigration from Mexico, Cuba, El Salvador and elsewhere in Hispanic America to the United States beginning in the second half of the 19th century to the present-day have strengthened the role of the Spanish language in the country. Today, Hispanics are one of the fastest growing demographics in the United States, thus increasing the use and importance of American Spanish in the United States.

Which acquisition reinforced the Spanish language?