The American South; Harlem, New York—In The 1930's
The narrator is born and raised in the American South, only to wind up in the New York City neighborhood of Harlem, which is a major center of African-American culture. The narrator finds the contrast between the North and the South incredible—he is amazed to find white drivers obeying the directives of a black policeman, on the subway he stresses out about being in close proximity to a white woman, and in the diner he wonders if it's insulting to tip a white waiter. In the North, then, the narrator experiences a certain amount of unprecedented racial freedom.
Or does he? His race is still the primary determinant in how he is perceived by others, whether by the higher-ups in an organization called the Brotherhood or by Sybil, a white self-proclaimed nymphomaniac who fantasizes about being raped by a black man. In his quest to uncover his identity, then, neither South nor North is particularly helpful.
Ultimately, it is only by descending into a manhole and remaining literally invisible to society that the narrator is able to operate in a setting that allows him to uncover the full range of his individuality.