Kenneth Harris spent most of his days in Atlanta yearning for a life in a place where his dark skin color is not a source of suspicion, but a mark of a shared heritage. His chance came two years ago when he bought a one-way ticket to Kenya. The 38-year-old retired veteran has found a community in the east African country’s capital, where he now runs an Airbnb business. He loves admiring Nairobi’s golden sunset from a rooftop terrace, and enjoys a luxurious lifestyle in a tastefully furnished apartment in an upmarket neighborhood. Harris is part of a growing wave...