and ancient Spanish settlement, which has considerable Mexican trade. It was originally an appanage to the old Spanish mission of St. Xavier, nine miles southward, and it now thrives on its cattle trade, mining and magnificent climate, being also the location of the Territorial University. To the northwest, in the well-irrigated valley of Salt River, is Phoenix, the capital of Arizona, with fifteen thousand population, the irrigation systems having produced great fertility in the adjacent region. The Salt River is a tributary of the Gila, the latter flowing out westward to the Colorado. In these Arizona valleys have been disclosed the remains of several prehistoric cities, chiefly located on a broad and sloping plain beginning at the confluence of the Salt with the Gila, and stretching down to the Mexican boundary. At Casa Grande is a famous ruin of a prehistoric temple with enormous adobé walls, the Government having made a reservation for its protection. These people were worshippers of the sun, and there have been discovered the remains of many towns with large population, the Gila Valley for ninety square miles disclosing these ruins, which are relics of the Stone age. Irrigation canals made by these prehistoric people, the oldest in the world, are also found throughout the region. Extensive explorations of these ancient cities have been made, and several have been named, among them Los Acequias, Los Muertos and Los Animos, the last being the largest, and there being strong evidence that it was destroyed by an earthquake which killed many thousands of the inhabitants. The railway follows the Gila Valley westward to its confluence with the Colorado, and here at the California boundary is Yuma, another of the early Spanish missions to the Indians, situated just north of the Mexican border, the Yuma Indians still living on a reservation adjoining the Colorado, their name meaning "the sons of the river." This town has its tragic history, for in 1781 the Indians made a savage raid upon the mission, destroyed the buildings and massacred the missionary priests.