The Californias, occasionally known as The Three Californias or Two Californias, are a region of North America spanning the United States and Mexico, consisting of the U.S. state of California and the Mexican states of Baja California and Baja California Sur. Historically, the term Californias was used to define the vast northwestern region of Spanish America, as the Province of the Californias, and later as a collective term for Alta California and the Baja California Peninsula.

The Baja California peninsula is a peninsula in northwestern Mexico. It separates the Gulf of California from the Pacific Ocean. The peninsula extends from Mexicali, Baja California, in the north to Cabo San Lucas, Baja California Sur, in the south.