This document discusses the Mexican population in the American Southwest following the Mexican-American War. It notes that in California, some Mexicans became rich during the Gold Rush but that by 1880 only one-fifth of California's population was Mexican. It also discusses the Tejano populations that remained in Texas cities like San Antonio, El Paso, and the Lower Rio Grande Valley, as well as the Mexican populations that continued to immigrate to Texas. Finally, it mentions the Mexican citizens who initially dominated Arizona and New Mexico and the Native American and growing Anglo populations in those territories following the Civil War and expansion of the railroad.