San Diego, the S. county of California, bounded E. by Arizona, from which it is separated by the Colorado river, S. by Lower California, and W. by the Pacific ocean; area, about 13,500 sq. m.; pop. in 1870, 4,951. Two branches of the Coast range cross it from N. to S., dividing it into three divisions differing much in climate, soil, and topography. The division along the coast is about 25 m. wide, and consists largely of level plains or gently sloping valleys, watered by the San Bernardo, San Diego, San Luis Rey, Margarita, Sweetwater, and other rivers; the greater portion is suitable for agriculture and grazing. The central or mountain division is very irregular in outline, averaging nearly 40 m. in width. Both ranges are covered with forests of oak, cedar, pine, and fir, and contain gold, silver, copper, and other minerals. Valuable gold mines have been opened within the past four years. Between them are a number of broad valleys or table lands, having a delightful climate and a fertile soil. They produce grapes, oranges, wheat, barley, etc. The E. division is occupied by the Colorado desert, which is for the most part treeless and barren, and part of it is below the level of the sea.
It is very dry and hot, and contains many natural curiosities, among which is a lake of boiling mud, about half a mile long by 500 yards wide. The chief productions in 1870 were 32,947 bushels of wheat, 9,330 of Indian corn, 18,745 of barley, 9,250 lbs. of wool, and 1,433 tons of hay. There were 5,687 horses, 1,268 milch cows, 20,347 other cattle, 16,443 sheep, and 1,683 swine. Capital, San Diego.
San Diego, a city, port of entry, and the capital of San Diego co., California, on the N. E. shore of a bay of the same name, about 460 m. S. E. of San Francisco, and 15 m. N. of the Mexican border; lat. 32° 44' 41" N., lon. 117° 8' W.; pop. in 1870, 2,300; in 1874, about 4,000. It has one of the three good harbors on the Pacific coast of the United States, and has been fixed by act of congress as the western terminus of the Texas and Pacific railroad. Its climate is remarkably equable and salubrious, the thermometer rarely rising to 80° F. or sinking to the freezing point. Many visit it as a health resort. The exports in 1874, consisting mainly of gold bullion, wool, wheat, flour, barley, hides, honey, wine, and olive oil, amounted to $2,000,000. There are four churches, two academies, two daily and two weekly newspapers, two banks, a fine court house, and a steam flouring mill. The city was laid out in 1868. - North San Diego, a small hamlet 4 m. N. of the city proper, was the first place settled by white men in California. Father Junípero, a Jesuit priest, with a number of followers, landed there in May, 1768, and soon afterward founded the mission of San Diego.