The province of the Californias was united until 1804, in the Spanish colonial Viceroyalty of New Spain, when it was divided into Alta (upper) and Baja (lower) California.

The two Californias division was kept after Mexican independence in 1821.
The Spanish Baja California Province became Mexican Baja California Territory, and remained a separate territory until 1836.
In 1836, the Siete Leyes constitutional reforms reunited both Californias in the Departamento de las Californias.
After 1848, the Baja California Peninsula again became a Mexican territory when Alta California was ceded to the United States (see 1854 map).

In 1931 Baja California Territory was divided into northern and southern territories.
In 1952, the "North Territory of Baja California" became the 29th State of Mexico as Baja California.
In 1974, the "South Territory of Baja California" became the 31st state as Baja California Sur.
The province of the Californias was united until 1804, in the Spanish colonial Viceroyalty of New Spain, when it was divided into Alta (upper) and Baja (lower) California.
The two Californias division was kept after Mexican independence in 1821. The Spanish Baja California Province became Mexican Baja California Territory, and remained a separate territory until 1836. In 1836, the Siete Leyes constitutional reforms reunited both Californias in the Departamento de las Californias. After 1848, the Baja California Peninsula again became a Mexican territory when Alta California was ceded to the United States (see 1854 map).
In 1931 Baja California Territory was divided into northern and southern territories. In 1952, the "North Territory of Baja California" became the 29th State of Mexico as Baja California. In 1974, the "South Territory of Baja California" became the 31st state as Baja California Sur.
Baja California Peninsula