Matamoros, city (1990 pop. 266,055), Tamaulipas state, NE Mexico, near the mouth of the Rio Grande, opposite Brownsville, Tex. Matamoros, linked by rail and highway with the United States, is an international trading center and a point of entry. The city is the center of an agricultural region that has become increasingly industrialized. Foreign-owned manufacturing plants, known as maquiladoras, proliferated in the area and constitute a dominant part of the economy. Founded in 1700 as San Juan de los Esteros, the city was renamed in 1851 in honor of the leader for Mexican independence Mariano Matamoros. Noted for its heroic defense against numerous U.S. adventurers during the 19th cent., the city fell to the forces of Zachary Taylor in the Mexican War in 1846.