In 1770 through royal orders and transfer of appropriate personnel José de Gálvez, Visitor General of New Spain, established a Spanish Naval Department on the Pacific Coast at a convenient location to send regular ships to the north. San Blas in what is today Nayarit was selected, though the location was far from ideal because of inadequate port characteristics. San Blas became a moderately satisfactory supply center with access to population areas of Jalisco and contacts via Guadalajara with Mexico City, the viceregal capital of New Spain. So closely was the area of San Blas associated with the newly founded area of Upper California, and marginally so with Lower California, that the new port became know as San Blas de Californias.
A logistic supply center such as San Blas was not only a depot for shipping goods to the north, it soon became a shipbuilding center and commercial area of some importance. As the missions of California progressed and as a moderate surplus of goods accumulated in the northern area, this port became the point of all products leaving California in legal trade. It served as a port of debarkation of furs from the Pacific Northwest, of agricultural products from California, and as a place through which many of the personnel coming to and going from California were obliged to pass. The syndics of the missions, the military supply officer of the California presidios, the commissary officer of the Spanish Naval Department, and other commercial agents made San Blas or nearby Tepic their headquarters.
 Jack S. Williams and
Thomas L. Davis, Sailors, Merchants, and Muleteers of the California
Mission Frontier, Rosen Publishing Group, Inc. 29 East 21st
Street, New York, NY 10010, PowerKids Press, 2004