TUCSON, a city and the capital of the territory of Arizona, county seat of Pima co., in lat. 32° 12′ N., lon. 110° 52′ W., 370 m. S. W. of Santa Fé, N. M., and the same distance E. by S. of San Diego, Cal., on the route between those places; pop. in 1870, 3,224; in 1875, about 5,000, three fourths of whom are of Mexican Origin and speak Spanish. It is situated in the valley of the Santa Cruz river, 2,520 ft. above the level of the sea, about 55 m. S. of the Gila river and 60 m. N. of the Mexican boundary, and is the largest and most important place in the territory. It has the appearance of a Mexican town, with the customary plazas and narrow streets and houses built chiefly of adobe; but with the accession of American population an improvement is taking place. Camp Lowell, a United States military post, is 7 m. distant. There is only one church, Roman Catholic. Nine miles S. of the city is the church of San Xavier, built upward of a century ago by Catholic missionaries. Tucson has a designated United States depository and money-order post office, and an assay office; a commodious and well furnished public school building, with male and female departments and a large and increasing attendance; a seminary and school, under the charge of the sisters of St. Joseph; and a weekly newspaper. The territorial library contains 3,000 volumes. The climate is mild in winter and hot in summer, the average temperature of January being 51° and of July 89°. The business in 1875 amounted to $1,800,000, consisting chiefly is trade with the Mexican state of Sonora, and in supplying the military posts and Indian reservations of S. Arizona.—Tucson is within the “Gadsden purchase,” obtained from Mexico by the treaty of Dec. 30, 1853. Its early history is unknown, but it has been a place of some importance for more than a century, and before its acquisition by the United States was a Mexican military post. It was incorporated in 1871.