How Manhattan’s Grid Grew
In 1811, John Randel created a proposed street grid of Manhattan. The New York Times has created a Google Map that allows you to compare Randel's map to modern-day Manhattan.
The map also includes an 1836 map of the farms of Manhattan, a map of street openings since 1642 and historic census data. Each of the maps is supplemented by a transparency slider that allows you to view the modern map underneath.
The map of street openings since 1642 allows you to visualise the growth of Manhattan. If you use the time-line control you can watch the spread of Mahattan from just a few streets to the present urban sprawl.