New Mexico, when it became a part of the territory of the United States, had a population made up of native and Mexican Indians, some of the latter having enough Spanish blood to cause them to consider themselves white men. The self-styled Spanish-American population of the present day is, properly speaking, composed of those whose ancestors were in the territory at the time of the Mexican War. The Spanish part of the description must be considered largely a courtesy title, for the amount of real Spanish blood in this hybrid population was always from a biological point of view nearly negligible, and the American part must be understood to mean native American Indians. The persistence of the Spanish language and culture is of course only a passing phase.
The Federal Census of 1850 credited New Mexico with 61,000 population not counting Indians, but the territory at that time included all of Arizona and Southeastern Colorado. By 1860 the population of the same territory was given at 82,979, plus 55,100 Indians. At this time there were less than 1200 natives of the United States in the whole territory.
Arizona had a fluctuating white population dependent upon the prosperity of the mining industry, but when the Federal troops were withdrawn at the outbreak of the Civil War most of the white men had to leave also. At that time the only real settlement was Tucson, where a few hundred Mexicans lived under mediæval conditions.
California had a population of Indians when the Spaniards coming from Mexico entered it. Most of them were of a very low order of intelligence and social development. The Spanish invaders were largely soldiers, and few of the members of these early expeditions brought their families. Hence, there was undoubtedly some mixing with the Indians from the very first days. In accordance with the custom elsewhere, those who had any white blood called themselves white, and the figures given by early writers for the number of Spanish in the colony must be understood in that light. The amount of real Spanish blood was extremely small and much of it was in the veins of missionaries who left no offspring.
The permanent population was made up of ex-soldiers who had settled down, married Indian women, and taken up land, together with occasional traders, vagabond sailors, and adventurers. The population of 1820 other than Indian could hardly have represented more than 500 men. The Mexican administration made an effort to supply women of Spanish ancestry to the colony in order to prevent too much matrimonial mixture with the Indians, which, even at that time, was regarded as somewhat disgraceful; but the number of brides who could be sent into a colony of that sort was small.
The population grew mainly by its own natural increase, and the small size of the Mexican population in California was one of the main factors that led to the incorporation of the territory in the United States. It has been computed that the "Spanish" population, most of which was of Indian blood, never exceeded 3000 persons. Prior to the American occupation there were not more than 1200 foreigners in California, three-fourths of whom were American and most of the remainder British. Thus this immense territory, which became a part of the United States in 1848 as a result of the Mexican War, was relatively empty. The amount of Spanish blood in the California population of today must therefore be quite negligible.
The whole trend of migration was changed by the discovery of gold at the end of 1848. In February of that year there were not more than 2000 Americans in all California. By the end of December there were 6000. By July of 1849 this number had grown to 15,000 and six months later it had climbed to 53,000. The earliest arrivals naturally came from the nearby regions. Oregon alone contributed more than 5000 from its scanty population. But every seaport of the Pacific sent a contingent, and the stream of men that poured into the gold fields was the most cosmopolitan group that had ever been seen in North America. In The New York Tribune for December 15, 1849, appears the following item from San Francisco:
"Foreign flags in the harbor: English, French, Portuguese, Italian, Hamburg, Bremen, Belgium, New Granadian, Dutch, Swedish, Oldenburgh, Chilean, Peruvian, Russian, Mexican, Hanoverian, Norwegian, Hawaiian, and Tahitian."