Colson Whitehead won the National Book Award for fiction on Wednesday night for “The Underground Railroad,” a hallucinatory novel about the horrors of American slavery and the sinister permutations of racism.

The novel, which became a best-seller and was selected for Oprah Winfrey’s book club, follows a young slave named Cora who escapes a Georgia plantation and, in a surreal twist, travels north via a literal underground subway.

In his acceptance speech, Mr. Whitehead said he was drawing comfort in these politically uncertain times by focusing on the redeeming power of art.