Baja California ( ), officially Free and Sovereign State of Baja California , is a state in Mexico. It 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 , or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California Peninsula, north of the 28th parallel, plus oceanic Guadalupe Island. The mainland portion of 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.

The Baja California Peninsula (, ) is a peninsula in Northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south. It ranges for at its narrowest to at its widest point and has approximately of coastline and approximately 65 islands. The total area of the Baja California Peninsula is .