Germantown Avenue divides Mt. Airy into two halves with different housing stock and different prices. West of the Avenue, 29 percent of single-family homes are detached and the median assessed value is $495,100. East of the Avenue, 44 percent are rowhouses and the median assessed value is $285,900. How densely the blocks are built and what the houses are worth account for most of what separates the two sides.
Both halves sit in one zip code, 19119, so nearly every published figure for Mt. Airy is a single median averaged across both. I built the interactive map below to show where the line runs and what sits on either side of the Avenue.
Which Side of the Avenue
Germantown Avenue is the line. Hover or tap either half to see what changes when you cross the Avenue.
Neighborhood boundaries from the OpenDataPhilly Philadelphia Neighborhoods dataset. Roads, rail lines, stations, creeks, the park and Wyndmoor from OpenStreetMap contributors, available under the ODbL. Housing counts, sizes and values come from the City of Philadelphia property assessment records, counting the single-family parcels in each half, July 2026. Assessed value is the city's figure rather than a sale price.
The line itself
Mt. Airy is in Northwest Philadelphia, between Germantown to the southeast and Chestnut Hill to the northwest. Cresheim Creek is the northern edge, the Wissahickon gorge the western one, Stenton Avenue the northeastern one. The southern edge is the one people argue about: common usage puts it at Johnson Street, while both neighborhood associations treat Washington Lane as the boundary with Germantown.
The boundary between the two halves runs down Germantown Avenue itself, matching the street almost exactly.
The Avenue also separates two different pieces of ground. On the west side, the land falls away toward the Wissahickon, which is why West Mt. Airy has winding streets, a heavy tree canopy, and the deep irregular lots that come from building on a slope. On the east side, the grid runs flat and regular out to Stenton Avenue. The street plans still show that difference.
Both halves share the Avenue itself. The shops, the restaurants, the 1928 Sedgwick Theater, and the three-block stretch the city added to the Philadelphia Register of Historic Places as the Central Mount Airy Commercial Historic District all sit on the border. Neither side owns the commercial heart. I wrote up my favorite stops along the Avenue separately, and almost nothing on that list belongs to one half.
What got built on each side
Prices follow the houses, so start with the houses. Here is every single-family home in each half, from the City of Philadelphia's property assessment records:
| West Mt. Airy | East Mt. Airy | |
|---|---|---|
| Single-family homes | 3,627 | 5,903 |
| Median size | 1,968 sq ft | 1,504 sq ft |
| Median lot | 3,287 sq ft | 2,400 sq ft |
| Detached singles | 29% | 12% |
| Twins | 36% | 43% |
| Rowhouses | 25% | 44% |
Source: City of Philadelphia property assessment records, pulled July 2026. Every single-family parcel inside each half, counted against the OpenDataPhilly neighborhood boundaries drawn on the map above.
East Mt. Airy is the larger half by about 2,300 homes, and the denser one. Rowhouses are 44 percent of East Mt. Airy's single-family stock against 25 percent on the west side, and detached houses are 12 percent against 29 percent. If you want a free-standing house with a yard on all four sides, the west side has roughly two and a half times the share of them, and its detached houses are larger: a median of 3,450 square feet on 13,256 square foot lots.
The two halves are closer in age than their prices suggest. Developers built across the whole neighborhood between roughly 1880 and 1920, putting up large houses for the upper middle class and twins and rows for everyone else, often within a few blocks of each other. West Mt. Airy has the 1890s Pelham development, with its gray-stone Victorians and Cotswold and Norman styling. East Mt. Airy has the Gowen estate blocks from the 1880s and Sedgwick Farms, laid out around 1905 and sold at the time as a suburb inside the city limits, which is where its Tudor revival houses come from. Both sides went up in the same decades, to different budgets.
So you are choosing a form of house more than a vintage, and the form drives what follows: the roof over it, what the systems cost to run, what you can add later. I went through how the roofs vary across Northwest Philadelphia if you want that version with shingles in it.
What the price difference buys
Comparing the same kind of house on each side shows what the gap is made of. These are medians, with the size of the house and the land under it alongside the value:
| Median, by house type | West Mt. Airy | East Mt. Airy |
|---|---|---|
| Rowhouse | $373,700 · 1,360 sq ft on a 1,611 sq ft lot | $224,100 · 1,242 sq ft on a 1,480 sq ft lot |
| Twin | $511,100 · 2,188 sq ft on a 3,650 sq ft lot | $333,500 · 1,706 sq ft on a 3,184 sq ft lot |
| Detached single | $821,500 · 3,450 sq ft on a 13,256 sq ft lot | $560,500 · 2,464 sq ft on an 8,787 sq ft lot |
Source: City of Philadelphia property assessment records, pulled July 2026. Assessed value is the city's figure for tax purposes, not a sale price.
A shared house type still covers a lot of variation. West Mt. Airy's detached homes run about 40 percent larger on lots about 50 percent bigger than East Mt. Airy's, and are assessed about 47 percent higher, so the house and the land account for most of that difference. Toward the entry level the sizes converge while the values do not: west rowhouses are about 10 percent larger on lots about 9 percent bigger, and assessed about two thirds higher. Across all single-family stock it works out to $249 per square foot on the west side against $185 on the east.
What assessment records do not capture is condition, finish, renovation history, or setting, and those vary house to house on both sides of the Avenue. Wissahickon frontage is part of what west-side buyers are paying for, along with the larger, more irregular lots that come with building on a slope.
Two caveats worth stating. Assessed value is the city's number, not a sale price, and assessments lag and smooth the market. Deeds actually recorded since July 2025 point the same way: a median of $543,000 across 95 sales on the west side, and $290,000 across 129 sales on the east. The transaction counts matter too. More trading happens on the east side, because more of the houses are there.
Two halves, two railroads
Each side has its own commuter railroad, and that goes back to two rival companies building north out of Center City in the 1800s.
West Mt. Airy rides the Chestnut Hill West Line, designated the R8 from 1984 until SEPTA dropped the R-numbers in 2010. The Pennsylvania Railroad built the line through a subsidiary, the Philadelphia, Germantown and Chestnut Hill Railroad, opened it on June 11, 1884, and ran it until 1976. Its trains came into Suburban Station. The stops here are Upsal, Carpenter, and Allen Lane.
East Mt. Airy rides the Chestnut Hill East Line, the old R7, which is the older railroad by fifty years. The earliest section dates to 1832, built by the Philadelphia, Germantown and Norristown Railroad, and the route belonged to the Reading Company from 1870 until 1976. Reading trains ran down the Reading Viaduct into Reading Terminal, a few blocks from the Pennsylvania's own terminal. The stops here are Mount Airy, Sedgwick, and Stenton.
So the Avenue divides two railroad suburbs that grew along competing tracks. Both lines reach Center City in roughly half an hour, they run on separate schedules, and which one you use is settled by which side of the Avenue your house is on. Bus routes cover both halves.
The civic history both halves share
Mt. Airy has a national reputation for community organizing, and both halves have the institutions to show for it.
West Mount Airy Neighbors was founded in 1959 under George Schermer, a resident who directed the City of Philadelphia's Human Relations Commission. East Mount Airy Neighbors organized in December 1965. Both groups worked on schools, zoning, and housing practices, and both are still operating today.
The practical result is a lot of civic activity on both sides of the Avenue: block associations that meet, zoning notices that get read, and two long-running neighborhood organizations with real membership. If you want the full history, Abigail Perkiss covers it in Making Good Neighbors (Cornell University Press, 2014), and the Encyclopedia of Greater Philadelphia has entries on West Mt. Airy and Northwest Philadelphia.
What each side offers
Most buyers I work with look at both halves before deciding. What usually settles it:
House form and lot size. West Mt. Airy has a much higher share of detached homes on large lots, and the largest houses in the neighborhood are there. East Mt. Airy is mostly twins and rowhouses on a tighter grid, in a wider range of sizes.
Inventory and pace. East Mt. Airy has about 2,300 more single-family homes and more recorded sales, so there is usually more on the market at any given moment and a deeper set of recent comparables to price against.
The Wissahickon. West Mt. Airy backs onto the park, and from much of it you can be on Forbidden Drive or in the woods on foot in a few minutes. East Mt. Airy is a drive or a long walk from the same trailheads. For some buyers that one factor decides it.
The train. Chestnut Hill West on the west side, Chestnut Hill East on the east, both about half an hour into Center City on separate schedules.
The same 1880s to 1920s stone-and-brick tradition runs through both halves, and the civic life described above is active on both sides of the Avenue. Which one fits comes down to what you want out of a house and a block.
If you are weighing the two, my Mt. Airy neighborhood guide has the current market data for Mt. Airy as a whole, and I am glad to walk either side with you.
Frequently Asked Questions
What is the difference between East and West Mt. Airy?
Germantown Avenue is the boundary. West Mt. Airy runs from the Avenue down to the Wissahickon gorge and holds 3,627 single-family homes with a median size of 1,968 square feet, a median lot of 3,287 square feet, and a median assessed value of $495,100. East Mt. Airy runs from the Avenue out to Stenton Avenue and holds 5,903 single-family homes with a median size of 1,504 square feet, a median lot of 2,400 square feet, and a median assessed value of $285,900. West has more detached houses on deeper lots, East has more rowhouses and twins on a tighter grid, and East is the larger half by roughly 2,300 homes.
Which street divides East and West Mt. Airy?
Germantown Avenue. The Avenue runs southeast to northwest through the neighborhood, and the boundary between the two halves follows the street almost exactly. Everything southwest of Germantown Avenue, down toward the Wissahickon Valley, is West Mt. Airy. Everything northeast of Germantown Avenue, out to Stenton Avenue, is East Mt. Airy. Both halves share the Avenue itself as their commercial spine, which is why the shops, restaurants, and the Sedgwick Theater belong to the whole neighborhood rather than to one side.
Is West Mt. Airy more expensive than East Mt. Airy?
Yes. The median assessed value is $495,100 in West Mt. Airy against $285,900 in East Mt. Airy, and deeds recorded since July 2025 run to a median of $543,000 on the west side against $290,000 on the east. Much of that reflects what is being bought. Comparing the same house type, West Mt. Airy's detached homes are about 40 percent larger on lots about 50 percent bigger, which accounts for most of the difference at that end of the market. Toward the entry level the sizes converge while the values do not. Assessment records do not capture condition, finish, or setting, which vary house to house on both sides.
Do East and West Mt. Airy have different train lines?
They do, and the split goes back to two rival railroads. West Mt. Airy is served by the Chestnut Hill West Line, designated the R8 from 1984 to 2010, which the Pennsylvania Railroad opened in 1884 and ran until 1976; its stops are Upsal, Carpenter, and Allen Lane. East Mt. Airy is served by the Chestnut Hill East Line, the old R7, whose oldest section dates to 1832 and which belonged to the Reading Company from 1870 to 1976; its stops are Mount Airy, Sedgwick, and Stenton. Both reach Center City in roughly half an hour, on separate schedules.
Which zip code covers East and West Mt. Airy?
Both halves sit in 19119, which is why most published market data treats Mt. Airy as one place and reports a single median for the whole neighborhood. That figure sits between two different markets and describes neither one well. Some of the area northeast of Stenton Avenue, past East Mt. Airy proper, falls into 19150 and is sometimes counted as Mt. Airy too.
