The new century saw a hardening of institutionalized racism and legal discrimination against citizens of African descent in the United States. Throughout this post Civil War period, racial stratification was informally and systemically enforced, in order to solidify the pre-existing social order. Although technically able to vote, poll taxes , pervasive acts of terror such as lynching in the United States (often perpetrated by groups such as the reborn Ku Klux Klan , founded in the Reconstruction South), and discriminatory laws such as grandfather clauses kept black Americans (and many poor whites ) disenfranchised particularly in the South. Furthermore, discrimination extended to state legislation that "allocated vastly unequal financial support" for black and white schools. In addition to this, county officials sometimes redistributed resources earmarked for blacks to white schools, further undermining educational opportunities.  In response to de jure racism, protest and lobbyist groups emerged, most notably, the NAACP (National Association for the Advancement of Colored People) in 1909. 
A combination of factors contributed to sequential pronounced rises in Mexican migration to the United States during the first three decades of the twentieth century. The Reclamation Act of 1902, which expanded acreage for farming through new irrigation projects, spurred the need for more agricultural laborers. The Mexican Revolution of 1910 and the aftermath of political instability and social violence caused many to flee northward across the border for their safety, and the growth of the . economy in the 1920s attracted additional numbers of immigrants. Though the wages received by most Mexican migrants in these decades were quite low, they were considerably higher than the salaries paid for comparable work in Mexico. Most importantly, the number of jobs for foreign laborers seemed unlimited, especially during World War I and on into the early 1920s.