Chamorro language
The Chamorro language is threatened, with a precipitous drop in language fluency over the past century. It is estimated that 75% of the population of Guam was literate in the Chamorro language around the time the United States captured the island during the Spanish–American War (there are no similar language fluency estimates for other areas of the Mariana Islands during this time). A century later, the 2000 U.S. Census showed that fewer than 20% of Chamorros living in Guam speak their heritage language fluently, and the vast majority of those were over the age of 55.