In 1846 a war erupted between Mexico and the United States, prompted by land-hungry North Americans, who wanted to obtain trading ports on the Pacific coast and to spread the wings of the eagle from Atlantic to Pacific. This conflict, which lasted only two years, resulted in the extension of the United States to the western coast. With the signing of the treaty ending the war -- the treaty of Guadalupe Hidalgo -- in 1848, the United States had succeeded in increasing its territory. Then, it had to face the difficult problem of dealing with an important provision of the agreement -- the many land titles granted by the Mexicans.
Before Mexico became independent from Spain in 1821, the vast domain in the southwestern section of the United States had been part of the Spanish Empire. The Spanish established settlements along the West Coast called missions, as a base to convert the Indians to Catholicism. In and around several pueblos, or large towns, Spain made large land grants to selected individuals to raise cattle. These ranchos were encouraged by their government, especially in California, which was well suited for this type of an economy. Ranchos were usually not well defined, and many of them lacked clear title. This system, which was continued by the Mexican government, resulted in a haphazard pattern of land ownership. It worked because there was no pressure from an expanding population. With plenty of land and few settlers, the undefined boundaries of the ranchos seldom came under dispute.