When Ronnia Cherry, 30, and Stefan Grant, 27, rented a house in Atlanta through Airbnb last year, they were caught off guard by police officers at their door, with guns drawn, responding to a neighbor’s report that they were thieves.

“We had to explain the owner gave us the security codes,” said Ms. Cherry, who, like Mr. Grant, is among the rising tide of black travelers decrying racist experiences while using the home-sharing service, and giving birth to the social media campaign #AirbnbWhileBlack.

The long-simmering issue was inflamed last month when an Airbnb host in North Carolina made hateful, racist posts in canceling a booking by a black guest.

It is the latest in a series of stories, both anecdotal and academic, regarding bias in the home-sharing system. In May, Gregory Selden, a black Airbnb user, turned to Twitter to share his experience of being turned down by a Philadelphia host. He posted that he then “made a fake profile as a white guy and was accepted immediately.” He has since filed a lawsuit against Airbnb, saying that it violated his civil rights.