San Juan is the largest municipality in American territory of Puerto Rico and is named after San Jan Bautista or St John the Baptist. A 2000 census reported San Juan's population to San Juan to be 433,733 and is the 42nd largest city under US jurisdiction. It is nicknamed 'La Ciudad Amurallada' (The Walled City). The city was originally called 'Puerto Rico (Rich Port)' and the entire island was called San Juan, the names were accidentally switched.

The wake of World War II saw San Juan undergo a significant economic growth. During that time, San Juan's economy relied heavily on companies dedicated to manufacturing. San Juan's products during that time included chemical substances (mostly house cleaning products), medicine, rum, fertilizers, and electrical tools.

Tourism is also a major industry in San Juan and it has served as a springboard for tourism around the island. It has helped bring attention to the Caribbean islands during the past 50 years. Today, San Juan boasts of a wide array of hotels, museums, restaurants, historical buildings, beaches, and shopping centers. San Juan attractions include Old San Juan, Ocean Park, Condado, and Isla Verde. Notable public figures have their roots in San Juan, these include Benicio del Toro, Raymond Ayala and Ricky Martin.