|Diego de Borica|
|Governor of Las Californias|
|Preceded by||José Joaquín de Arrillaga|
|Succeeded by||Pere d'Alberní i Teixidor|
Diego de Borica was a Basque Spanish explorer and the seventh governor of Las Californias from 1794 to 1800, and is credited by some authors with defining Alta- and Baja-California's official borders. Others hold José Joaquín de Arrillaga responsible for designing that territorial division in 1804.
Diego de Borica y Retegui was born in Vitoria-Gasteiz to a family holding ties with the one of Fermin Lasuén. In 1780 Diego de Borica married Maria Magdalena de Urquidi, a Mexican-Basque and direct descendant of one of the founders of Durango, Mexico.
As the governor, Diego de Borica and Father Fermín Lasuén determined that five more missions were needed in 1795 along El Camino Real. Borica sent expeditions from four different missions to find suitable new settlements that were no more than one day's travel as military escorts were necessary. By August 1796, Borica notified Viceroy Miguel de la Grúa Talamanca that no increase in troops was necessary. The first missionary site selected in 1796 was Mission San José near the pueblo of the same name.
In 1797, Borica ordered the construction of a battery to protect the cove east of Point Medanos. The location initially was named "Bateria San Jose" and was chosen because the promontory overlooked San Francisco Bay and Alcatraz Island. Borica provisioned the unit with five brass cannons.
On orders from Viceroy La Grúa Talamanca, Borica established a school grounds at the center of Villa de Branciforte in 1797. Also in 1797, he granted José María Verdugo's retirement. Verdugo was the grantee of Rancho San Rafael.
Borica was a member of the Royal Basque Society and well under the influence of the Enlightenment's ideas of progress (cf. circumstances in the Basque districts back in Europe), showing a concern for the welfare of his subjects. However, his attempts to establish settlements in California—for which purpose he thought of Catalans—and launch the economic development of California were largely foiled by the Spanish Crown's failure to back up his effort.
At a time when the publications of the Royal Basque Society encouraged sheep raising and wool growing, Borica fostered maximum autonomy for the Californian missions by spreading sheep among the ranchers, engaging even personally in that pursuit. He was successful during his office, but by the time of California's detachment from Mexico, flocks had diminished significantly.