The usual way that race labels are applied in the United States in everyday parlance and in government statistics fail to capture a phemenon poised to reshape how race is actually lived in America: the increase in multiracial marriages and births, which almost certainly will lead to more blended populations in future generations. As this trend continues, it will blur the racial fault lines of the last half of the twentieth century. The nation is not there yet. But the evidence for multiracial marriages and multiracial individual identity shows an unmistakable softening of boundaries that should lead to new ways of thinking about racial populations and race-related issues.

Sociologists have viewed multiracial marriage as a benchmark for the ultimate stage of assimilation of a particular group into society. For that to occur, members of the group will already have reached other milestones: facility with a common language, similar levels of education, regular interaction in the workplace and community, and, especially, some level of residential integration. This is what we saw with European immigrants from Italy, Poland, and Russia in the last century. After decades of being kept at arm’s length by “old” European groups such as those from Britain, Germany, and Scandinavia, the newer arrivals finally began to intermarry with the more established ethnic groups as they became more upwardly mobile and geographically dispersed. Hispanics and Asians differ from white Europeans, of course—most significantly, for these purposes, Americans tend to view them as racial groups rather than ethnic groups. And race divisions, especially between whites and blacks, have historically been far less permeable. So the blending of today’s new racial minorities through multiracial marriage is breaking new ground.

Multiracial marriages have been rising dramatically. In 1960 (before federal statistics enumerated Hispanics and before the 1965 legislation that opened up immigration to more countries) multiracial marriages constituted only 0.4 percent of all U.S. marriages. That figure increased to 3.2 percent in 1980 and to 8.4 percent in 2010. More than one in seven newlywed couples are now multiracial.

Amid this overall increase, the propensity to marry out of one’s racial or ethnicity varies. Among recently married whites, 17 percent were married to someone of another race, but for Hispanics and Asians, more than four in ten recent marriages are multiracial. Among minorities,blacks continues to have the lowest prevalence of multiracial marriages, a legacy of the anti-miscegenation statutes that persisted in 16 states until 1967, when the Supreme Court declared them unconstitutional in the landmark Loving v. Virginia decision. It was only after this ruling in the post–civil rights environment that black multiracial marriages began to rise noticeably, but among recent, typically younger marriages involving blacks, nearly three in ten were multiracial marriages, signaling an important breakthrough in the long history of black marital endogamy.

Especially noteworthy is the rise in white-black multiracial marriages: In 1960, white-black marriages amounted to only 1.7 percent of all black same-race marriages, but in 2010, they amounted to 12 percent. White-black relationships are even more prevalent among recent cohabiting couples.

The geographic dispersion of new minority populations to the New Sun Belt states in the South and Mountain West—and into the largely white, interior Heartland states—is dispersing multiracial marriages along with it. The highest prevalence of multiracial marriages is found in Hawaii, where three in ten marriages are multiracial, followed by Alaska and Oklahoma. These states have long-standing populations of Asians, Alaska Natives, and American Indians, respectively. Just below are a mix of states where Hispanic and Asian immigrants have maintained a long-term presence, including New Mexico, California, Texas, Washington, Oregon, Arizona, Nevada, and Colorado. At least one in ten marriages in these states is multiracial. Multiracial marriages are also growing in the New Sun Belt (states such as Georgia, Utah, Idaho, and North Carolina) and even several Heartland states (Minnesota, Connecticut, Pennsylvania, and Indiana). Although many new Hispanic migrants to these regions are less assimilated than elsewhere with regard to measures such as English language proficiency and education, they are likely to have substantial interaction with their states’ non-Hispanic populations, which may be leading to more multiracial marriages than might otherwise occur. For example, in Idaho and Utah, the prevalence of multiracial marriages among Hispanics is 43 and 44 percent, respectively. These rates stand in contrast to rates of 26 and 21 percent in the more mature Melting Pot states of California and Texas.

At the other end of the spectrum are 14 states where multiracial marriages account for less than 5 percent of all marriages. In West Virginia, only about 3 in 100 marriages are multiracial. 

An obvious consequence of a rise in multiracial marriages would be an increase in multiracial children, which would lead to a greater share of the population claiming a mix of racial backgrounds. The marriage of individuals from various European immigrant backgrounds led to the melting pot that characterizes much of today’s white population. It would seem only natural to anticipate a similar boom of multiracial persons in the years ahead. Yet in the case of multiracial marriages, national and cultural boundaries are not the only lines being crossed. New ground is being broken, pushing back against long-standing social and even legal constraints that often subjugated multiracial persons—particularly those with white-black ancestry—to second-class status. In many cases, individuals who could “pass” as white tried to do so in order to become part of the mainstream.

The practice of dividing whites from blacks and other nonwhites began in the early years of nationhood, when the slave population was counted separately and the “one drop” rule stipulated that if a person had any black ancestors, they could not be classified as white. Although classifications in later censuses included Chinese, Japanese, Filipino, and Hindu, there was little attempt to think of these largely “racial” categories as subject to mixing. This stands in contrast to the collection of information on parental birthplace and ancestry or national origin, which was widely used to study the blending of white ethnic populations. Although multiracial populations emanating from multiracial marriages certainly existed, they were not well documented in national statistics.

Beginning with the 2000 census, federal guidelines mandated that when U.S. government statistical agencies collect information on race, they must provide options for persons who identify with more than one race. The impetus for this change came from a well-organized grassroots effort by people who thought of themselves as multiracial and wanted to be officially recognized as such.

The census permits identification of combinations of up to six specific racial categories, including “some other race,” a catch-all category for those races not specifically identified. In 2010, those identifying as “white and black” made up the largest single group—a population that more than doubled over the preceding decade, especially among the young. For every 100 black toddlers under age five, 15 toddlers are identified as both white and black—a sharp rise since 2000. In a handful of Western, Great Plains and New England states, the population of “white and black” persons is more than 20 percent of the black-only population.

But the more vivid evidence of the erosion of the white-black divide is found in the South, the region historically most resistant to racial change. Because of past prejudices and customs, the white-black population, as a percentage of all blacks, is still considerably lower in the South than in other parts of the country. In a slew of states from Maryland to Texas, “white and black” populations amount to less than 5 percent of the black-only populations; in Mississippi and Louisiana, “white and black” populations constitute only 1 percent. Yet the South is attracting blacks in large numbers, including multiracial blacks, from all parts of the country. And when states are ranked by the growth in their “white-black” multiracial populations in the first decade of the 2000s, rather than their current totals, the southern states lead all others. In that period, the Carolinas, Georgia, Mississippi, and Alabama more than tripled their white-black multiracial populations. Tennessee, Florida, Arkansas, Louisiana, and Kentucky were not far behind. In fact, southern states as a whole accounted for 41 percent of the nation’s decade-long gain in the “white and black” multiracial population.

Overall, the share of the U.S. total population that categorizes itself as multiracial—2.9 percent—is surprisingly small in light of the pervasiveness of multiracial marriages.There are several reasons to believe that the official numbers markedly understate size. One is that the census does not include Hispanics in its count of multiracial persons because they are considered an ethnic rather than a racial group. After the 2010 census, the Census Bureau began to experiment with the implications of changing this policy. It allowed respondents to choose new multiracial categories such as “white and Hispanic” or “black and Hispanic.” This change led, in one scenario, to a rise in the multiracial share of the population to 6.8 percent, well above the 2.9 percent in the 2010 census. Moreover, earlier projections using a similar approach by non-census researchers show the U.S. multiracial population reaching 10 percent in the year 2020 and 18 percent in the year 2050.

A second reason why the multiracial population may be going undercounted is that the single racial status of children is often determined by the adult who fills out the census form. Research suggests that in identifying the race of their children, multiracial couples often select single-race identities that they believe will be more socially acceptable or will better prepare their children for success. This, of course, may change as these children come of age and begin defining themselves. President Barack Obama, the child of a multiracial marriage, announced through his spokesperson that he identified himself as “black” rather than “white and black” on his 2010 census form. It is likely, however, that younger and future generations of Americans from multiracial families will be more likely to embrace their heritage.

Reprinted with permission from Diversity Explosion: How New Racial Demographics are Remaking America by William H. Frey (Brookings Press, 2014).