Before the Treaty of Guadalupe Hidalgo, Mexicans were generally considered white in legal terms. The treaty allowed Mexicans to become U.S. citizens, which classified them as "incorporated into the Union" and legally white. However, in practice, many Mexicans faced discrimination and were often treated as foreigners, which contradicted the legal classification. The Treaty's provisions aimed to integrate Mexicans into the U.S. but did not fully protect their rights, leading to ongoing challenges in their social and legal status.