After William Penn laid out his plan for Philadelphia with surveyor Thomas Holme in 1683, most of the streets running east-west were named after trees.

It’s not known why that happened, but the names fit neatly into the efforts of Philadelphia’s first real estate developer to market the city as a “greene Country Towne."

North to south, the streets were Vine, Sassafras (now Race), Mulberry (now Arch), High (now Market), Chestnut, Walnut, Locust, Spruce, Pine, and Cedar (now South).

Cherry Street arrived later, appearing in William Birch’s 1800 Plan of Philadelphia between Sassafras and Mulberry Streets. Others also appeared, but they were not named after trees, including Sansom, which was made up of connecting alleys with different names.

A recent question to Curious Philly — the forum through which we answer queries from readers about the city and region — asked about a statement that appears to be city lore: “Is it true that Philly’s streets named after trees are in order from north to south, hardwood to softwood?”

On a basic classification level, the answer is yes — if we remove Vine from consideration, since vines are not trees.

Sassafras, cherry, mulberry, chestnut, walnut, and locust are hardwoods, while spruce, pine and cedar are softwoods. In general, hardwoods come from deciduous trees that lose their leaves annually, and evergreen conifers produce softwoods.

William Birch's 1800 "Plan of the City of Philadelphia."
Public Domain
William Birch's 1800 "Plan of the City of Philadelphia."

There is no record to indicate whether the hardwood to softwood arrangement was planned or simply coincidental.

“I’ve never heard this, but I wouldn’t put it past Penn to have thought this way since he came from a family with serious gardening interests,” said Elizabeth Milroy, a Drexel University art history professor and author of The Grid and the River: Philadelphia’s Green Places, 1682-1876.

“Trouble is, we don’t know for sure that [Penn] named the streets — it could easily have been Holme,” she said. “All Penn says in his description is that these are trees that grew in the area.”

Tom Reber, director of landscapes and facilities at Bartram’s Garden, said he’s heard the hardwood-softwood “urban myth.”

“My sense is that the names were chosen from the most readily available and valuable timbers of the Delaware Valley at the time,” Reber said. "The grouping by hardwood/softwood is logical as this follows basic tree and timber classification.”

» MORE CURIOUS PHILLY: Some Philly street signs have a Liberty Bell. Here’s how it got there.

As to whether the trees listed are ordered by having the most-dense wood to least-dense wood, there is no way to ascertain that.

“For just about all the trees in the list you could question which species the common name really refers to," said Joel Fry, curator and historian at Bartram’s Garden. “There is a single species of sassafras, but all the others — cherry, mulberry, chestnut, walnut, locust, pine, cedar — could be correlated with two or more species, each with different densities.”

How north-south streets came to be counted

On the subject of street designations in Penn’s original city, it is largely forgotten that the north-south streets west of Broad Street had different names than they do now and were the source of some confusion to out-of-towners back in the day.

Until the mid-19th century, streets west of Broad were numbered from the Schuylkill, with the street closest to the river known as Schuylkill Front Street and the last one before Broad designated as Schuylkill Eighth Street.

In December 1853, two months before the city and the multiple entities making up the County of Philadelphia were consolidated, the city government decided that starting the count of numbered streets from the Delaware River made sense.

As a result, Schuylkill Eighth Street became 15th Street and so on going west. Broad Street, in turn became the 14th street in the grid while never being given that designation. Fourteenth Street simply does not exist in Philly.

Editor’s note: This story was revised to remove the name Filbert from a mention of streets not named after trees. Filbert is an alternative name for hazelnut.