Chilean writer Isabel Allende has warned that "the values and principles that sustain our civilisation are under siege".
Speaking at the National Book Awards, the author of The House of the Spirits spoke out about the rise of "nationalism and racism" in politics.
She was handed a lifetime achievement prize at the ceremony in New York.
"This is a dark time, my friends," Allende said during her acceptance speech.
'Violence and poverty'
"A time of nationalism and racism; of cruelty and fanaticism. A time when the values and principles that sustain our civilisation are under siege.
"It's a time of violence and poverty for many; masses of people, who are forced to leave everything that is familiar to them and undertake dangerous journeys to save their lives."
Allende was born in Chile, but spent 13 years living as a political refugee in Venezuela before moving to the United States. In 1982 she published her debut novel, The House of the Spirits, which brought her literary acclaim.
She dedicated her award to the "millions of people like myself who have come to this country in search of a new life."
Grief and a Great Dane
The top prize for fiction was given to Sigrid Nunez's The Friend: about a writer grieving for the loss of her best friend and mentor, as she inherits the giant Great Dane dog he left behind.
"For a writer, nothing is ever quite as bad as it is for other people because, however dreadful, it may be of use," she said as she accepted the award, quoting the British writer Alan Bennett.
Jeffrey C Stewart took home the non-fiction award for The New Negro: The Life of Alain Locke, a biography of the writer and philosopher who became the first black Rhodes scholar in 1907, and is regarded as the "father" of the 1920s Harlem Renaissance.
Race and sexuality are also at the heart of Justin Phillip Reed's Indecency, which took the poetry prize, while the life of a Dominican family in Harlem forms the backbone of Elizabeth Acevedo's novel, The Poet X, which is written as a series of slam poems and won the prize for Young People's Literature.
This year's awards added a category for works in translation, which was won by Japanese-German author Yoko Tawada's The Emissary, translated by Margaret Mitsutani.
The dystopian novel is set in near-future Japan, in a society where children are becoming increasingly infirm as the elderly prosper.