Manhattan’s grid pattern was a response to the population growth between 1790 and 1810. Public health issues increased as a result so some action was needed. It focused on the downtown areas because most of the city’s population lived there. Its main goal was to be structured but flexible. It took about 60 years for the grid to be built up to 155th street, during which many factors (administration, aesthetic values, interest groups) changed and could have undermined the plan. It caused a debate among New Yorkers (property owners in particular). More than 720 buildings were demolished or moved, which caused the city to lose most of its original architectural history.