The island of Puerto Rico, is a self-governing territory of the United States located in the Caribbean, east of the Dominican Republic and west of the Virgin Islands. San Juan is the capital and largest municipality in Puerto Rico. Today, it serves as one of Puerto Rico's most important seaports, and is the island's cultural, and tourism center. The population of the metro area includes San Juan and nine surrounding municipalities. About half the population of Puerto Rico now lives and works in this area. San Juan, Ponce, Mayaguez and Aquadilla are amongst the largest cities island-wide.