The rapid increase in the Hispanic population has not, however, complicated the black-white binary of U.S. race relations to the extent one might have expected. In part, this is because middle-class Hispanics–with the assistance of the Census Bureau in 1980–have redrawn the boundaries of whiteness to include both Hispanics and “non-Hispanic whites.” Mexican Americans, like other Hispanic groups, are at a crossroads: one path, slouching toward whiteness, leads to racial fissures that harden the color line between blacks and whites. Hispanic whites express their new sense of entitlement often by supporting anti-affirmative action laws, English-only movements, and other nativist ideologies on the backs of immigrants and African Americans. Another path welcomes the shared responsibility of defining and bringing into existence a transnational multiracial identity that acknowledges the Indian and African heritage of Latinos and their ancient ties to the Western hemisphere, an identity that the author Richard Rodriguez calls simply “brown.”
Neil Foley, "Partly Colored or Other White: Mexican Americans and Their Problem with the Color Line," in Beyond Black and White: Race, Ethnicity, and Gender in the U.S. South and Southwest
, ed. Stephanie Cole and Alison M. Parker, 123-144 (College Station: Texas A&M University Press, 204), 141.
“The Third Enlargement of American Whiteness,” post-1945. “Included now were Mexicans and Mexican Americans … Since the mid-1930s, federal and Texas state laws had defined Mexicans as white and allowed them to vote in Texas’s white primary.”
The Second World War rearranged Americans by the millions. […] Louis Adamic had dreamed of a second, more homogenized immigrant generation, and one had already started in the Civilian Conservation Corps, fruit of the New Deal’s earliest days. Now, a decade later, millions rather than tens of thousands left home.
Let us remember that this mixing occurred with several notable exceptions. Black Americans–who numbered some 13.3 million in 1940–were, of course, largely excluded. Their time would come much later, and with revolutionary urgency. But also excluded were Asian Americans. Even so, other Americans–provided they qualified as white for federal purposes–experienced a revolution of their own. Indeed, the white category itself had expanded enormously, well beyond European immigrants and their children. Included now were Mexicans and Mexican Americans.
 The handsome Julio Martinez from San Antonio plays a leading role in the multicultural Army squad of Norman Mailer’s best-selling war novel The Naked and the Dead (1948). […] Since the mid-1930s, federal and Texas state laws had defined Mexicans as white and allowed them to vote in Texas’s white primary. While Asian American and African American service personnel were routinely segregated and mistreated, Mexican Americans fought in white units and appeared in the media of war, witness the boom in popular war movies like Bataan (1944), staring the Cuban Desi Arnaz (who in the 1950s would become a television star as Lucille Ball’s husband in the long-running I Love Lucy series).
Nell Irvin Painter, The History of White People
(New York: W.W. Norton & Company, 2010), 359-360.
(N.B.: this account is largely wrong, and symptomatic of an all-too-frequent mistake in the historical studies of expanding constructions of whiteness)