AMERICANAH. By Chimamanda Ngozi Adichie. Knopf. 496 pages. $26.95.

WE NEED NEW NAMES. By NoViolet Bulawayo. Reagan Arthur Books (Little Brown Company). 296 pages. $25.

It has been pointed out that more Africans have come to North America in the last 20 years or so than during the entire two centuries when the slave trade was legal.

That deliberately startling statistic is, of course, misleading since unlike their 17th- and 18th-century predecessors, the contemporary number of voluntary African immigrants represents a tiny fraction of this country’s population, but it does draw attention to Africa as a source of immigration to the U.S. by people of color.

Like immigrants from other parts of the developing world whose stories are more widely known, these 21st-century African arrivals are variously fleeing political instability, violence, economic breakdown or any combination of those.

Unlike their enslaved precursors, they know where they are going (or think they do): they are often already very worldly and well-educated, fluent in at least one European language and well-versed in global pop culture.

And they often have particular notions of America typical of other immigrants drawn to this country. Yes, they see it as the land of the free and a place of opportunity, but they also see it as a place whose endemic racism is the source of fear: of the possibility of physical and psychological violence.

It is a place where the color of their skin will make a material difference, and where their complex personal identity, defined by their ethnicity, education, prior status, etc., will be replaced by their simplistic reduction into the category of “black.”

Such themes provided the content for Chimamanda Ngozi Adichie’s 2008 collection of short stories “The Thing Around Your Neck.” Now, in her third full-length novel, “Americanah,” Adichie puts the immigrant experience of young Nigerians center-stage: the talented and ambitious young Ifemelu leaves Nigeria on a student visa in the 1990s to avoid the brutality, corruption and social collapse of General Sani Abacha’s regime.

Given the chaos back home and the legal limitations on her once in the U.S., she finds herself with little option but to accept illegal employment, in situations rife with the potential for exploitation, and extremely damaging to self-esteem and psychological well-being.

Thus, even when she (like her creator) eventually wins fame and fortune blogging about the experience of “non-American blacks” she hankers for home and the high school love of her life, whose parallel experience in the U.K. Adichie very deftly interweaves into the story.

Even in superficially satisfying and happy relationships with a wealthy white man and then a high-profile African-American academic, her persistent consciousness of difference, racial and ethnic, respectively, finally drives her back to Nigeria and to Obinze.

In what might be merely soap-opera or melodrama in the hands of a lesser writer, the two childhood sweethearts pick up where they had left off more than a decade earlier by embarking on an affair that is both absolutely right and absolutely wrong.

Although Adichie leaves the two lovers together at the end of the novel, there is no sense that their future is secure. Indeed, the greater sense is that the damage caused by emigration/exile has returned to further undermine the longed-for stability of home.

NoViolet Bulawayo’s debut novel, “We Need New Names,” is even more challenging, the odds against her narrator’s ultimate success even more starkly stacked against her. Although Bulawayo’s feisty Darling, like Ifemelu, is well-educated, fluent in English and in global culture, and thus superficially familiar with American life, she starts from a more completely failed state, Zimbabwe, where the economic and political collapse has led to an almost complete erosion of values beyond the necessity to survive.

When she arrives in the U.S., she rapidly realizes that the envied aunt she stays with is living far more precariously than she had ever imagined. Her disillusioned experience of America draws attention to broad social differences between African and American ways of life: the communality that mitigated material deprivation back home in Zimbabwe, on the one hand, the cold of winter and tastelessness of pre-packaged food in America on the other hand. Both narrators feel the sting of American arrogance and ignorance about their home continent.

But whereas Ifemelu uses her eventual success to return to a Nigeria that is politically and economically on the mend, allowing the resumption of her relationship, however unsatisfactory, with Obinze, Bulawayo’s Darling remains entirely adrift in exile.

“We Need New Names” ends with an entirely unsatisfactory Skype call to Darling’s childhood friend, Chipo, who blasts her for having left Zimbabwe: “Tell me, do you abandon your house because it’s burning,” she asks, “or do you find water to put out the fire?”

At this moment of rage and self-alienation, her aunt’s lover bursts in with the news that Osama bin Laden has been killed. His announcement prompts the novel’s final scene, Darling’s childhood memory of seeing the dog Ncuncu run over by a bread truck. The scene is graphically described.

It is a disturbing image of vulnerability jarringly juxtaposed with the “delicious, delicious smell of Lobels bread.” The new African immigrants to America may not be reduced to chattel status like their 17th- and 18th-century precursors, but in these two compelling stories of supposedly voluntary migration, Adichie and Bulawayo suggest that the move from Africa to America can still be violently disruptive.

Reviewer Simon Lewis is a professor of African literature at the College of Charleston.