Despite what you may think today, Philadelphia was America’s first planned city. William Penn had a broad vision for the new settlement and started a revolution in city planning: the open grid plan that became Philadelphia. Having witnessed plague in London in 1665 and the famously calamitous fire of 1666, Penn wanted his Philadelphia to be ‘a greene countrie towne, which will never be burnt, and allways be wholsome.‘ The way he proposed to achieve this was as simple as it was revolutionary: the grid. This innovation in city planning led to Philadelphia quickly becoming the largest city in the New World. Soon scores of new American cities adopted his blueprint:
The grid had a purpose beyond a mere abstract, geometric exercise. Orderly space, Penn believed, would shape an orderly society. Rational space, rational people. Rectilinear geometry would be Penn’s way of keeping the city’s density low, or at least lower than the packed crowded conditions typical of most European cities, and of creating spacious building lots with trees on them. The grid was the shape of utopia. More than that, the plan embodied Penn’s vision of “brotherly love” through what it did not include: a wall or any other fortifications. City walls were on the wane in Europe as the medieval world passed into the modern one, but they were certainly still regarded as a necessity in the rough frontier of America. Penn believed, however, that his would be a city of peace, and thus Philadelphia was founded to be an open city.
As originally envisioned in the grid, the city looked inward on itself toward Center Square in the middle, without privileging a few sites over others. Other ideas for city planning swirled in the seventeenth century, but most attempted to organize space for grand displays of power. L’Enfant’s very baroque design of Washington, D.C., with its overwide diagonals cutting through its rectilinear grid, reflects a design intend to display power. There is nothing baroque about Penn’s grid.
While he held title to a very large tract of land, Penn set aside roughly two square miles for his ‘great towne.‘ He then subdivided within those boundaries into a regular, orderly grid. Streets ran straight, north and south, east and west, and intersected at right angles. The two widest streets—now called Market and Broad were “more commodious than any street in seventeenth-century London.” This novel design constituted the most dramatic act of urban planning in the West since the Romans positioning Philadelphian as a clear product of the Enlightenment.