The imposition of the American system of race relations proved detrimental to many inhabitants of the newly acquired territories. Texas had already demonstrated as much. Mexico had abolished slavery and declared persons of Spanish, Indian, and African origin equal before the law. The Texas constitution adopted after independence not only included protections for slavery but also denied civil rights to Indians and persons of African origin. Only whites were permitted to purchase land, and the entrance of free blacks into the state was prohibited altogether. “Every privilege dear to a free man is taken away,” one free black resident of Texas complained.
Local circumstances affected racial definitions in the former Mexican territories. Texas defined “Spanish” Mexicans, especially those who occupied important social positions, as white.
The residents of New Mexico of both Mexican and Indian origin, on the other hand, were long deemed “too Mexican” for democratic self-government. With white migration lagging, Congress did not allow New Mexico to become a state until 1912.