A crucial step in the evolution of modern plant agriculture was the development of low-cost, energy-efficient greenhouse structures that provide optimum growing conditions year-round. In 1964, Professor William J. Roberts developed the first air-inflated double-layer polyethylene greenhouse covering system at Cook College, Rutgers University.
The City Plan of Philadelphia is a seminal creation in American city planning in that it was the first American City Plan to provide open public squares for the free enjoyment of the community and a gridiron street pattern featuring streets of varying widths: wide main streets and narrower side streets. In addition this plan was the first city plan in the United States to provide for long-term urban growth. These features inspired the planners of many cities to adopt the Philadelphia Plan as a model.