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How is Harlem in the 19th and 20th century? Why does the author suggest that the tenements be rebuilt?
In the 19th century: there were public roads, fine mansions and asphalt streets. Farms gradually disappeared.
In the 20th century: Harlem is a large, thickly populated urban community - a city within city, with fine streets and avenues, parks, playgrounds, churches, schools, apartment houses, theaters
The author suggests that the tenements be rebuilt because they are now firetraps (buildings that would be hard to escape from if they were on fire)