Baja California, officially Free and Sovereign State of Baja California (Spanish: Estado Libre y Soberano de Baja California), is the northernmost and westernmost of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state in 1953, the area was known as the North Territory of Baja California (El Territorio Norte de Baja California). It has an area of 70,113 km2 (27,071 sq mi), or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California peninsula, north of the 28th parallel. The state is bordered on the west by the Pacific Ocean, on the east by Sonora, the U.S. State of Arizona, and the Gulf of California (also known as the Sea of Cortez), and on the south by Baja California Sur. Its northern limit is the U.S. state of California.