When some 19th-century. New Yorkers said' Harlem', they meant almost all of Manhattan above Eighty-sixth Street. Toward the end of the century, however, a group of citizens in upper Manhattan — wanting, perhaps, to shape a closer and more precise sense of community — designated a section that they wished to be known as Harlem. The chosen area was the Harlem to which Blacks were moving in the first decades of the new century as they left their old settlements on the middle and lower blocks of the West Side. As the community became predominantly Black, the very word 'Harlem' seemed to lose its old meaning. At times, it was easy to forget that 'Harlem' was originally the Dutch name 'Harrlem', that the community it described had been founded by people from Holland and that for most cites three centuries — it was first settled in the sixteen hundred it had been occupied by White New Yorkers. 'Harlem' became synonymous with Black life and Black style. in Manhattan. Blacks living there used the word as though they had coined it themselves — not only to designate their area of residence but to express their sense of the various of its life and atmosphere. As the years passed, 'Harlem' assumed an even larger meaning. In the words of Adam Clayton Powell, the pastor of the Abyssinian Baptist Church, Harlem 'became the symbol of liberty and the promised land to the Negroes. Everywhere'. By 1919, Harlem's population had grown by several thousand. It had received its share of wartime migration from the South, the Caribbean, and parts of colonial Africa. Some of the new arrivals merely lived in Harlem. It was New York they had come to, looking for jobs and for all the other legendary opportunities of life in the city. To others who migrated to Harlem, New York was merely the city in which they found themselves Harlem was exactly where they wished to be. What is the main subject of the passage?