Puerto Rico is an unincorporated US territory. The US won the island from Spain in the Spanish-American War along with the Philippines and Guam, so it is also referred to as a colonial possession, specifically by the UN's Decolonization Committee.
Many US states were territories the US gained in wars. The territories ceded in the Mexican-American War had large numbers of Mexican citizens living in them, for example. Has Puerto Rico experienced fewer privileges and autonomy than other US territories? What were commonly the rights and treatment of the people like in US territories in the Continental US?