The oil business has developed in waves; as new fields are discovered, individuals and companies rush to that area to seek their fortunes. In the United States just after the turn of the century, the wave headed for Texas and Oklahoma, and shortly thereafter, turned farther south toward the Mexican Gulf Coast. Despite the fact that between 1910 and 1920 Mexico was going through a major revolution, entrepreneurs, engineers, geologists, and skilled workers from the American Southwest poured into the area and participated in bringing Mexican oil production up to 25.2 percent of total world production in 1921, at the same time raising United States participation in the Mexican oil industry from 38.5 percent of a total investment of $51,900,000 U.S. in 1911 to 61 percent of $819,600,000 U.S. ten years later. This effort was both dangerous and romantic for the participants, and for many of them the profits were substantial. Needless to say, the relationship between the United States and Mexico was considerably affected by this influx of capital and personnel, and was made particularly crucial by the advent of the First World War in Europe. By the end of the decade, it had become clear that oil had paid a significant part of the cost of the Mexican Revolution and that future institutionalization by the Mexican government would depend greatly on oil revenues. Further, North American companies had gained preeminence in the industry, in large part because of the men who went to Mexico from the American Southwest.