The government of Puerto Rico encompasses the local administrative structure of the archipelago and island of Puerto Rico, an unincorporated territory of the U.S. organized under the Constitution of Puerto Rico since its establishment as the Commonwealth of Puerto Rico in 1952. The government is a republican democracy divided into three branches: the law-implementing executive, the law-making legislative, and the law-interpreting judicial. The Governor is the chief executive, the Legislative Assembly is the legislature, and the Supreme Court is the highest court of the territory, which is divided into 78 municipalities, each one headed by a strong mayor and a unicameral legislature. Like U.S. states and other U.S. territories, Puerto Rico is subject to the sovereign jurisdiction of the U.S. federal government.
With the American annexation of Puerto Rico during the Spanish–American War, the U.S. established a military government to administer the unincorporated territory from 1898 to 1900, when it was replaced by a civil insular government organized under the organic acts of the Foraker Act from 1900 to 1917 and the Jones–Shafroth Act from 1917 to 1952. The Constitution of Puerto Rico established the Commonwealth of Puerto Rico and its government under the continued status of unincorporated territory in 1952. With the ratification of the constitution, the full authority and responsibility for the local administration of Puerto Rico was vested in the residents of Puerto Rico, resulting in complete self-governance within the archipelago and island.