User: Given this text, what are the oldest and newest major territories of the United States?
Assistant: The United States has five major territories. Guam, American Samoa, Northern Mariana Islands, Puerto Rico, and U.S. Virgin Islands. Of those, the two oldest are Guam, and Puerto Rico; both being acquired in 1899 at the end of the Spanish - American War. The Northern Mariana Islands is the newest of the five major territories, joining the United States in 1986.