The novel is set in the late 19th and early 20th century, a tumultuous time in the history of racial politics in the United States. The Emancipation Proclamation declared an end to slavery in 1863, in the midst of the Civil War. Emancipation was enforced gradually over the next two and a half years, until finally it was illegal in practice for people to remain enslaved throughout the United States. The "Reconstruction Era" followed the Civil War and lasted until 1877. During this period, there were enormous gains in Black political power throughout the country. In the South, state legislatures saw their first Black representatives elected.
By the end of the 19th century, though, there was enormous white supremacist backlash against the newfound political power Black people were exercising for the first time. The years during which the novel is set saw massive, organized campaigns of terror against Black people, especially in the South. On top of this physical violence, political activists organized to roll back the gains of Reconstruction. Black people saw their voting rights stripped down so that they could no longer participate in representative democracy, as they had done for the decade following the Civil War. The 13th, 14th, and 15th amendments to the U.S. Constitution, which were written to extend protections to Black people as citizens, were all but repealed.
The "ex-colored man" grows up during this time. He spends most of his childhood in Connecticut, where he experiences racism but is largely sheltered from the worst of it. His (white) father helped his (Black) mother move from Georgia to Connecticut around the time things took a turn for the worse for Black people in the South. The narrator spends much of the novel realizing how bad things have gotten for Black people in the United States. His travels in Europe help him realize the severity of the problem. Although people often expect social progress to be linear, the narrator observes the opposite. After witnessing a brutal lynching in Chapter 10, he decides once and for all that he should use his light-skinned complexion to pass for white.