In rupturing the black-white polarity of southern race relations, the presence of Mexicans in central Texas raises some interesting questions about the way in which “whiteness” itself fissured along race and class lines. White Texans had a long history of invoking the color line in their social, economic, and political interactions with African Americans, but they had little experience in plantation society with what one contemporary sociologist called “partly colored races.” Were partly colored Mexicans, in other words, white or nonwhite? As a racially mixed group, Mexicans, like Indians or Asians, lived in a black-and-white nation that regarded them neither as black nor as white. Although small numbers of Mexicans–usually light-skinned, middle-class Mexican Americans–claimed to be Spanish and therefore white, the overwhelming majority of Texas whites regarded Mexicans as a “mongrelized” race of Indian, African, and Spanish ancestry. In Texas, unlike in other parts of the South, whiteness meant not only not black but also not Mexican.
Neil Foley, The White Scourge: Mexicans, Blacks, and Poor Whites in Texas Cotton Culture
(Berkeley: University of California Press, 1997), 5.
In 2016, American Latinxs are non-white / brown / people of color:
Thirty-one percent of eligible voters will be racial or ethnic minorities, up from 29% in 2012, according to the Pew Research Center. And the share of non-Hispanic white voters eligible to vote will be the lowest in history, the continuation of a steady decline in white voters over the past three decades.
It’s a stark reminder of the shifting demographics of the country: The Census Bureau projects that no one racial group will be a majority of the country by the year 2044. Republicans and Democrats looking to chart an electoral future as the country continues to grow browner and younger will have to take heed of these shifts.
In the 1980 presidential election, white voters made up 88% of the electorate. That year, Ronald Reagan won 56% of non-Hispanic whites and captured the presidential election in a landslide. Four years later, against Walter Mondale, Reagan won them by 30 points, 66% to 34%. Since Reagan’s time though, the white share of the electorate has declined by a few percentage points each presidential year.
Why the white vote’s shrinking
One reason is because overall, the white population in the United States is growing older and the younger generations of Americans are increasingly diverse, fueled largely by the growth of the Latino population in the US.
Familiarity of African-American vs. alienness of Mexican as ethnic outgroup, Southern culture. / BB&W 127.
By the middle of the 1930s it was clear in Texas and other parts of the American West that African Americans did not constitute the number one  race problem, as they had historically in the states of the South, including East Texas. In the West the threat to whiteness came principally from Latin America, particularly Mexico, not from Africa or African Americans. African Americans, after all, were not “alien” or foreign, and whites had a long history of dealing with blacks. In Texas and other southern states, whites and blacks had grown up together in the same towns, even if Jim Crow laws prevented them from sitting at the same lunch counters or attending the same schools. Blacks, for their part, shared much of southern culture with whites, whether on cotton farms or in Baptist churches. Indeed, African Americans in Texas shared wit hwhites the experience of being displaced from their farms by Mexican immigrants whose language, religion, and customs differed from those of both blacks and whites.
Blacks, whatever else they might be to whites, were therefore not “alien,” a word reserved by nativists to describe immigrants. Although many Mexicans had lived in Texas long before Stephen Austin established the first Anglo settlement in 1822, Anglos still regarded Mexicans as alien culturally, linguistically, religiously, and racially.
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), 126-127.
Becoming White, then, is not an either/or proposition, but rather it is an uneven process, resulting in racial identities that change across contexts and time. Thus, in the 1920s eastern and southern Europeans could be White for purposes of naturalization, but still racial inferiors in the close context of immigration and the more general milieu of social relations. […] Recall now the question that opened this book. Judge  Smith in Shahid asked: “Then, what is white?” The above discussion suggests some answers. Whiteness is a social construct, a legal artifact, a function of white people believe, a mutable category tied to particular historical moments. Other answers are also possible. “White” is an idea, an evolving social group, an unstable identity subject to expansion and contraction, a trope for welcome immigrant groups, a mechanism for excluding those of unfamiliar origin, an artifice of social prejudice. Indeed, Whiteness can be one, all, or any combination of these, depending on the local setting in which it is deployed. On the other hand, in light of the prerequisite cases, some answers are no longer acceptable. “White” is not a biologically defined group, a neutral designation of difference, an objective description of immutable traits, a scientifically defensible division of humankind, an accident of nature unmolded by the hands of people. In the end, the prerequisite cases leave us with this: “white” is common knowledge. “White” is what we believe it is.
Ian F. Haney López, White By Law: The Legal Construction of Race
(New York: New York University Press, 1996), 80-81.
Transparency phenomenon of whiteness. / WBL, p. 22.
Not all White scholars suffer from the same myopia regarding Whiteness. Indeed, Barbara Flagg introduces her article on White race-consciousness, “Was Blind, But Now I See”: White Race Consciousness and the Requirement of Discriminating Intent, by criticizing other White authors for their singular focus on Blacks. Importantly, Flagg suggests that the exclusive focus on Blacks is more than an innocent mistake. She argues that it is a contingent, particularly revealing error, a function of the nature of White race-consciousness rather than a fortuitous slip. Flagg fits this myopia into her theory of White race-consciousness by suggesting that there exists a tendency among Whites not to see themselves in racial terms. She identifies this tendency as one of the defining characteristics of being White, and labels this the “transparency phenomenon.” “The most striking characteristic of whites’ consciousness of whiteness is that most of the time we don’t have any. I call this the transparency phenomenon: the tendency of whites not to think about whiteness, or about norms, behaviors, experiences, or perspectives that are white-specific.” Flagg argues that as an antidote to transparency, Whites must develop “a carefully conceived race consciousness, one that begins with whites’ consciousness of whiteness.” In this critique and in her prescription for change, Flagg is almost certainly correct. Her article advances the thinking on race-consciousness by  placing Whites securely within the parameters of discussion and by identifying a central hurdle that must be surmounted in the development of White racial self-awareness.
If transparency is a common phenomenon among Whites today, it seems also to have afflicted judges deciding prerequisite cases. Despite the apparent simplicity of the issue before them, the courts hearing prerequisite cases experienced great difficulty defining who was White, often turning for succor to such disparate materials as amici briefs, encyclopedias, and anthropological texts. Even with the assistance of these materials, however, the courts hearing prerequisite cases were slow to develop a defensible definition of Whiteness, instead frequently reaching contradictory results. Though themselves White, judges hearing prerequisite cases could not easily say what distinguishes a “white person.” More than a few judges expressed considerable consternation over the indeterminacy of the prerequisite language in its reference to “whites.” Thus, in a 1913 case, Ex parte Shahid, a federal court in South Carolina protested that “[t]he statute as it stands is most uncertain, ambiguous, and difficult both of construction and application.” Shahid posed in frustration the beguilingly simple question that introduces this book: “Then, what is white?”
Ian F. Haney López, White By Law: The Legal Construction of Race
(New York: New York University Press, 1996), 22-23.