Dutch edition of William Penn and Thomas Holme’s first plan for Philadelphia, 1684. | Image courtesy of the Free Library of Philadelphia

Philadelphia was laid out as a planned city by William Penn and Thomas Holme. Having witnessed the aftermath of the Great Fire of London, Penn envisioned an orderly, verdant city with a green space in each quadrant. Penn and Holme expected balanced settlement on the banks of both the Schuylkill and Delaware Rivers. Thwarting this orderly vision right from the beginning, the city developed exclusively along the Delaware River with the greatest density closest to the port. The precisely laid out square parcels were subdivided and alleys were cut into the uniform street grid.

The density close to river had deadly implications when mosquitoes carrying yellow fever stowed away on ships arriving from the Caribbean. Sailors residing in a boarding house near the port were the first to fall to the disease. During the summer and fall of 1793, nearly 10 percent of the city’s population perished. Hardest hit were the poor who could not afford to flee to safer territory in the city’s outskirts. The streets and alleys closest to the wharf were the red zones of 1793. Thus the built environment significantly impacted the spread of the disease. The yellow fever epidemic likewise influenced the built environment.

Washington Square

Washington Square originally served as a burial ground. During the yellow fever epidemic 1,300 victims were buried there. In 1816 work began to reestablish the potter’s field into a public park. | Photo: Michael Bixler

Although the yellow fever epidemic hit hardest close to the river, its greatest short-term physical impact was on an area a few blocks to the west, the square planned for the southeast quadrant of Philadelphia.

In 1793, Southeast Square was a potter’s field. Remote from the bustling portside city, since 1706 it had been a burial ground for strangers, suicides, and both free and enslaved black people. Although African Americans could sometimes worship in white churches, they could not be laid to rest in their cemeteries. Nicknamed Congo Square, the potter’s field was also a gathering place for the city’s black population.

During the Revolutionary War, hundreds of soldiers were buried in the square after dying at the notorious Walnut Street Jail. Completed in 1775, the jail ran from Walnut to Locust (then called Prune Street) along 6th Street. Scores of imprisoned American soldiers perished during the British occupation of Philadelphia. Once the city was liberated by the Continental Army, it was the Redcoats’ turn to suffer.

The earliest building on the square was the Loganian Library on the northwest corner of 6th and Walnut. Built in 1754, it housed the impressive book and document collection of Pennsylvania’s leading statesman, James Logan. In 1792, the contents were transferred to the Library Company of Philadelphia where they remain today. In 1793, the Loganian Library became an orphanage for children who lost their parents to the epidemic.

More significantly for the development of what we now call Washington Square, 1,300 yellow fever victims were buried in the potter’s field, so many corpses that the city declared it full to capacity. Macabre though this may sound, Southeast Square was rapidly transformed from a mass grave into an upscale neighborhood of row houses.

This lithograph from 1838 gives a bird’s-eye view of Washington Square, originally named Southeast Square, and points south from the steeple of Independence Hall (Pennsylvania State House). Efforts to transform the square from a potter’s field to a public park began in 1816. The park was renamed Washington Square in 1825. | Image courtesy of Print and Picture Collection, Free Library of Philadelphia

In 1797, William Sansom bought land at auction on which he constructed the city’s first purposely built set of uniform row houses. Designed by the country’s first certified architect Benjamin Latrobe, Sansom Row was also the first speculative development in the city. The buildings at 705 and 707 Walnut Street still survive and are the oldest buildings on the square. Other townhouses soon followed.

Rather than people being attracted to living on the square, affluent people moved to the homes and then demanded that the former potter’s field be transformed into a park. The City complied. Walkways were installed and in 1816 it was formally landscaped with 200 trees. In 1825, the park was named Washington Square.

Residents on the newly fashionable square included Nicholas Biddle, president of the Second Bank of the United States, Horace Furness–Shakespeare scholar and brother of architect Frank Furness–Joseph Bonaparte, and Commodore Barry.

The Walnut Street Jail was demolished in 1838. On a parcel of the former prison’s footprint, the Athenaeum of Philadelphia was constructed in 1847 as the first Italianate building in the city. The collection of this private library was moved here from the American Philosophical Society where it had been housed for 32 years.

A map from 1858 depicts a square fully encircled by houses with only three exceptions: the Athenaeum, the Second Presbyterian Church, and the Orange Street Meeting House. Yes, Washington Square was likely destined to become something more than a potter’s field, but the yellow fever epidemic certainly sped up the timetable.

The Lazaretto Quarantine Station

Lazaretto Quarantine Station at Wanamaker Avenue and East Second Street in Tinicum Township. Date unknown. Restoration of the complex was recently completed and the building is open to the public for tours. | Photo: Historic American Buildings Survey, Prints and Photographs Division, Library of Congress

Following the devastation of 1793 and several smaller yellow fever outbreaks later that decade, a Philadelphia Board of Health was established. In 1799, the board ordered the construction of a complex of buildings on an island in the Delaware River about seven miles south of Philadelphia in Tinicum Township. The Lazaretto was the nation’s first inspection and quarantine station. Ships bound for the port of Philadelphia were required to stop at the Lazaretto for examination of both the cargo and the people on board. Sick sailors and passengers were quarantined in the Lazaretto’s hospital before proceeding to the city. Those who died were buried at the site’s graveyard. Although not as well-known as Ellis Island, the Lazaretto was also once the leading point of entry for immigrants to the United States.

At the turn of the 20th century, the Lazaretto was closed as a quarantine station. The property was used for recreation by the Philadelphia Athletic Club and later as an airfield. In 2006, a compromise was reached between Tinicum Township and the Preservation Alliance for Greater Philadelphia to maintain the Lazaretto buildings while also allowing for development on the land. It is the oldest surviving quarantine station in the United States.

The Lazaretto, a 2016 historical novel by Diane McKinney-Whetstone, vividly depicts life among an interracial group of staff and inmates during the post-Civil War era.

Fairmount Water Works

Fairmount Water Works was built between 1812 and 1872 and designed by Frederick Graff. | Photo: Michael Bixler

In addition to the Board of Health, a Watering Committee was established in the aftermath of the yellow fever epidemic. In 1799, a steam-powered water treatment system was designed by Benjamin Latrobe. Schuylkill River water was pumped in through a brick tunnel into holding tanks at Centre Square, the eventual site of City Hall. The water was purified and then distributed through a system of pipes made of hollowed logs. Latrobe’s innovation established the nation’s first municipal water supply, and the lovely Neoclassical pumping station became a popular gathering place.

A side note about Benjamin Latrobe: After finishing the Philadelphia water system project, his friend President Thomas Jefferson hired him to superintend the construction of the U.S. Capitol. He also designed the White House portico and several other DC landmarks. Latrobe later engineered a water system for New Orleans similar to the Centre Square pumping station. After 11 years of construction, the New Orleans water works system was completed in 1819. In 1820, Latrobe died in Louisiana. The cause was yellow fever.

By 1811, the Centre Square station could no longer meet the needs of the growing city. A new steam powered pumping station was erected, this time near the Schuylkill River. The Farimount Water Works pumped water from the Schuylkill River into a reservoir on Fair Mount. Gravity fed pipes sent water to the rest of the city.

A hand-colored engraving on wood depicting the Pump House in Centre Square, which is now the location of City Hall. | Image courtesy of Print and Picture Collection, Free Library of Philadelphia

The Fairmount Water Works was both an architectural and technological wonder. Fairmount had formally been property of the Penn family and was peppered with elegant summer homes for Philadelphia’s elite. The Fairmount Water Works echoed the graceful opulence of these residences. In 1819, hydropower replaced steam power when a spillway dam, the nation’s largest, was put in place across the Schuylkill River.

City residents and visitors flocked to the site to admire the beautiful setting, the picturesque Greek Revival architecture, and the impressive technology. During the 19th century, Philadelphia’s Fairmount Water Works was second only to Niagra Falls as the nation’s most popular tourist attraction. In the 1850s, Fairmount Park was established in order to protect the segment of the Schuylkill River’s watershed that provided clean water to the city.

The Fairmount Water Works was decommissioned in 1909. The Philadelphia Museum of Art was built on the site of the former reservoir and in a style to complement the buildings of the attractive water treatment facility. The Benjamin Franklin Parkway, which recently celebrated its 100th birthday, was laid out along a route that connects the Philadelphia Museum of Art to City Hall.

So really, if you think about it, no yellow fever, no Parkway. It is worth considering how different our city might look if scientists had not taken until 1900 to understand that mosquitoes, not unclean water, were the cause of yellow fever.

Losing Capital Status

The First Bank of the United States at 128 South 3rd Street was built in 1795 and designed by Samuel Blodgett. | Photo: Michael Bixler

The biggest impact on Philadelphia’s built environment is, however, what did not happen in the years following the yellow fever epidemic. In 1793, Philadelphia was the financial center of the United States. The first Bank of the United States and the first stock exchange were located here. The port of Philadelphia was among the busiest in North America. After yellow fever, however, other cities embargoed goods coming from Philadelphia and merchants were wary of sending cargo to the city. In 1796, New York overtook Philadelphia in the value of imports. A year later, it exceeded our city in exports.

Furthermore, in 1793 Philadelphia was the capital of both Pennsylvania and the United States. When yellow fever struck, the federal and state governments fled to places like Germantown and Grays Ferry. George Washington’s household moved to the Deshler Morris House, the so-called Germantown White House. In 1799, the state capital was moved to Lancaster, far from the fetid, and potentially disease-infested city. And the national capital, of course, was relocated to Washington, D.C. in 1800.

If Philadelphia had become an economic powerhouse akin to New York City, or the national capital like Washington, D.C., it is unlikely that it would have developed as the walkable, neighborhood-based, blue collar, and proudly parochial city that we love.

We know we are living through a dramatic chapter in history. How the city’s built environment will change remains to be seen. A recent Philadelphia Inquirer article by architecture critic Inga Saffron speculates that as a result of Covid-19 we may see even fewer brick and mortar stores, a diminished demand for new office buildings, and the shuttering of movie theaters. Like the connection between yellow fever and the Parkway, however, we all may be long gone by the time Covid-19’s lasting impact on our city can be discerned.

For more on the yellow fever outbreak watch the episode “Fever: 1793” from the history series Philadelphia: The Great Experiment. Video courtesy of Making History Productions.