For decades, liberals complained that American society is segregated because rich, white people don't want to live in ethnically-mixed neighborhoods. Sometimes, liberals had a point. From the 1930s to 1960s, as rich white people moved into New York City, urban planner Robert Moses got city bureaucrats to condemn and destroy busy black neighborhoods. The city called the neighborhoods "blighted" and moved many of the poor into rent-subsidized apartment complexes called "projects." Many quickly became slums. Now times have changed. Some rich, white people want to move into poorer, non-white neighborhoods because they like diversity (and cheaper real estate). So today, writes John Stossel, the newcomers are attacked by liberals because they cause "gentrification."