The concept of the slum emerged when industrial capitalism hit its stride in the late 19th century. Derived from Cockney street slang, the word was soon taken up by reformers and moralists of the Victorian period, a loaded descriptor of the densely populated and poorly serviced neighborhoods that housed workers, their families, and the reserve army of the unemployed.
Plenty of people used the word “slum” with the best of intentions, but it is notable that very few have used it to describe their own neighborhoods. A slum is a place to be ministered to, a place to be cleaned up, a place to be cleared out. A “dark continent that is within easy walking distance of the General Post office,” as one 19th-century writer put it.