Mexicans have historically used and manipulated race to improve their social status.
This isn't to say that race has had no social meaning in Mexican history. From the 16th to the 19th centuries, Spain imposed a hierarchical racial order in colonial Mexico, one that favored those with European heritage and lighter skin. Whites, blacks, mestizos and Indians were assigned different levels of access to property, power and prestige. But through the years, racial mixing eroded the categories and weakened that social order. As the categories loosened, upwardly mobile Mexicans gamed the system and climbed the racial ladder by creative categorization. This was most common on Mexico's northern frontier--the contemporary American Southwest--where government control was weak and most pioneers were mestizo. In California and Texas, settlers routinely reclassified themselves to improve their social standing. The first two census surveys of the pueblo of Los Angeles are full of instances of racial re-classification.
In 1781, a certain Jose Vanegas was classified as Indian. Nine years later, however, he is listed as a mestizo. Similarly, while the first census lists Jose Navarro as mestizo, in 1790, he has become a Spaniard instead.