Baja California is the northernmost state of México. It is sometimes incorrectly referred to as Baja California Norte to distinguish it from the Baja California peninsula, of which it forms the northern half, and Baja California Sur, which forms the southern half of the peninsula. Before becoming a state in 1953, the area was known as the Territory of Baja California Norte. It has an area of 71,576 km2 (about 27,600 mi2,) or 3.57% of the land mass of México. The state is bordered on the west by the Pacific Ocean, on the east by Sonora and the Sea of Cortéz or Gulf of California, and on the south by Baja California Sur. Its northern limit is the U.S.-México border, adjacent to the U.S. state of California.
The state has a population of 2,750,000 (2003 estimate), much more than the sparsely populated Baja California Sur to the south. Over 75% of the population live in the capital city, Mexicali, or the most populous city in the state, Tijuana. Both these cities are close to the U.S. border. Other important cities include Ensenada, San Felipe, Playas de Rosarito and Tecate.

History of Baja California
 |
1690s–1700s: Spanish settlement in California. |
 |
1804: The Spanish colony of California is divided into Alta ("upper") and Baja ("lower") California at the line separating the Franciscan missions in the north from the Dominican missions in the south. |
 |
In 1850, after Alta California is annexed by the United States, Baja California is further divided into northern and southern territories. |
 |
1952: Northern Baja California becomes the 29th state of México. The southern portion, below 28°N, remains a federally administered territory. |
 |
1974: The southern territory becomes the 31st state, Baja California Sur. |
 |
1989: Ernesto Ruffo Appel of the PAN becomes the first non-PRI governor of Baja California and the first opposition governor of any state since the Revolution. | |