SEPTA is looking to redevelop the Mifflin Substation at the intersection of East Passyunk Avenue, South 13th Street, and Morris Street, inviting developers and neighbors alike to reimagine the building.
The property, located at 1831-37 S. 13th St., is the Mifflin Substation.
What's left behind is a striking industrial shell. SEPTA's project documentation describes 35-foot ceilings, massive windows, and an open main floor, plus a full basement that adds to the building's redevelopment potential. “It's definitely a place of its time,” Jennifer Dougherty said, per the Inquirer's reporting.
The substation opened in 1914 under the Philadelphia Rapid Transit Co., which reorganized as the Philadelphia Transportation Co. in 1940 before SEPTA absorbed it in 1968. Its trolley-power role outlasted the Route 23 fixed-track trolley, which was replaced by diesel buses in 1992. The building was de-energized in 2003, as the company’s transit history shows.
A Potential New Use for East Passyunk
SEPTA isn't treating this as a one-off real estate play. The agency plans to redevelop the Mifflin Substation through its Transit Oriented Communities program, which has also been used for projects at Ambler and Conshohocken Regional Rail stations.
SEPTA defines its Transit Oriented Communities program as broader than station-area construction: it also covers land-use planning, multimodal access, walking and micromobility, and coordination with local communities. The agency says the program aims to support equitable, sustainable development that allows more people to live and work near transit. That puts Mifflin within an effort that pairs use of SEPTA property with community planning and better access to transit, as SEPTA’s program description explains.
SEPTA expects the Mifflin project to generate income and create a new asset for the East Passyunk Avenue area, and the numbers suggest why developers might bite. SEPTA's own market analysis found that annual consumer spending within a one-mile radius of the substation totals approximately $1.27 billion, concentrated heavily in dining, entertainment, and leisure.
What Could Fill the Space
The eventual use of the building remains open. Whoever ultimately wins the redevelopment job will lease the property from SEPTA and rebuild it, rather than purchasing it outright.
In nearby Pennsport, a former PECO electrical substation at 538 Federal St. was converted into a 21-unit luxury apartment building called The Lumen.
A nearby model shows both the scale and the trade-offs in SEPTA’s lease approach. In February 2026, the agency selected Korman Communities and Benchmark Real Estate for a 99-year ground lease at Ambler Station, valued at $236 million. Their proposal includes multifamily housing with an affordable component, ground-floor commercial space and public open space. The Mifflin building is a different, smaller reuse challenge, but the Ambler deal illustrates how SEPTA can retain land ownership while seeking long-term revenue and community benefits, as the Ambler project terms show.
Zoning Limits
Any redeveloper will have to work within CMX-2.5 Neighborhood Commercial Mixed-Use zoning, which SEPTA's project materials confirm applies to the site. Philadelphia's zoning code caps CMX-2.5 building heights at 38 feet, though developers can pursue height and density bonuses by including mixed-income affordable housing or contributing to the Philadelphia Housing Trust Fund, according to a legal analysis from Nochumson P.C.
The Mifflin Substation is not currently listed on local or national historic registers, though a developer could pursue historic designation to unlock tax credits down the line.
Residents Get Their Say in December
SEPTA plans to invite community input on an adaptive reuse concept. A public open house is anticipated in December 2026.
For East Passyunk, the Mifflin Substation's fate will hinge on what residents want to see — and what a developer is willing to build.
