You will be given a definition of a task first, then some input of the task.
Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: Jacksonville, like most large cities in the United States, suffered from negative effects of rapid urban sprawl after World War II. The construction of highways led residents to move to newer housing in the suburbs. After World War II, the government of the city of Jacksonville began to increase spending to fund new public building projects in the boom that occurred after the war. Mayor W. Haydon Burns' Jacksonville Story resulted in the construction of a new city hall, civic auditorium, public library and other projects that created a dynamic sense of civic pride. However, the development of suburbs and a subsequent wave of middle class 'white flight' left Jacksonville with a much poorer population than before. The city's most populous ethnic group, non-Hispanic white, declined from 75.8% in 1970 to 55.1% by 2010. Question: What term referred to middle class citizens leaving the suburbs?
Output:
white flight