Urban Planning 101 – Border Vacuums


Folsom Powerhouse is between phases, Awesometown is soon to begin and Pop is selling… Sure we’ve got Duplexcellence II to worry about but that still leaves us with some free time to get back to blogging. So we’ve decided to pick back up with Jane Jacobs and continue our Urban Planning 101 series. This time we’ve been reviewing “Border Vacuums”, which are a cool concept especially in conjunction with mixed use neighborhoods. Cool, like new rubber bands on your braces cool.

So what exactly are border vacuums? And where can I get one?

Yes, it is a great name for an as seen on tv product but, “Border Vacuum” is really just a simple urbanist term used to describe  any long, single use territory.  I-676 for example as it cuts through Center City and particularly Old City is a border vacuum.  The Delaware river, I-95 and our network of rail lines are all classic examples of Border Vacuums. Less obvious are large shopping plaza’s, parking garages and blocks of solely 9-5 office towers. In all cases these areas form borders for pedestrian activity. Their single use, although it may be a pedestrian draw like the 9-5 office tower, creates a void in the otherwise chaotic variety of uses that makes a city exciting.

As the variety of uses declines so will the number of pedestrians on the street. The border vacuum has the effect of sucking the life out of the city directly adjacent to it. That’s where Jacobs got the vacuum part of the term… we assume. Either way the effect of border vacuums is the creation of an edge, where pedestrian life forms a void and everything lies quiet.

To help us visualize this, and because even we wouldn’t read this if it wasn’t broken up with pictures, we made a map of Philadelphia with all the borders as defined by Jacobs removed from the map. First we took out the rivers, the most obvious borders, then large stretches of open space, the used and unused rail lines, large highways, and really wide streets. What we are left with is a city divided up into smaller sections.

If we were to compare this to a map of Philadelphia’s neighborhoods we would see that many of the neighborhood boundaries are the border vacuums we’re talking about. This doesn’t work exactly for every neighborhood and some of the zones on our map may contain 2 or 3 neighborhoods, but as long as you don’t hold us to a strict interpretation, this remains true. Now before we start arguing about where your neighborhood begins and ends I should mention that neighborhood boundaries aren’t an official designation. Neighborhoods, aren’t even an official designation. After all you don’t cross a line and go through customs but they do sell different kinds of  beer and the ethnicity of the ethnic food has changed. So uhh, disclaimers aside, once we zoom in you can see those “neighborhoods” take shape. (FYI in these zoomed in maps we removed giant shopping plazas and parking lots as well since they are also borders. It was too much work to do for all of Philadelphia.)

Borders are important in defining neighborhoods but clearly a lot of what lets you know you’re in a new neighborhood is the disparity between them.  Whatever it is, one neighborhood has a different feel than the other. One might feel safe, the other kinda iffy, one might be bustling with people while the other may be mostly trash tubleweeds. This is where “Mixed Use” comes into play. If you’re a loyal follower of our blog you already know from our first Urban Planning 101 post that “Mixed use” is the backbone of a healthy neighborhood. But in case you forgot exactly what that means; mixed use neighborhoods are neighborhoods that have a variety of uses (Residential, Commercial, Civic, Industrial,). Not exactly an earth shattering concept, but the important thing behind it is that a mixed use neighborhood will have pedestrian activity on the street at all times of day; people going to work in the morning, doing some shopping in the afternoon and going out for a drink at night. Having people on the street is what keeps it safe and interesting. Take a look at those same three neighborhoods but now with commercial space overlayed on top. Info courtesy of google maps.

In these three neighborhoods you’ll notice a line of yellow starts to emerge. That’s what we’d call a commercial corridor, and it’s the hub of pedestrian activity. From our perspective as developers, Philadelphia seems to range from these healthy urban neighborhoods with a lot of pedestrian activity, the ones seeing massive redevelopment, to sadly unhealthy neighborhoods that have changed little since the loss of population that shook Philadelphia from a city of 2 million in 1950 to a city of 1.5 million 50 years later.

This dichotomy occurs where it does largely as a result of border vacuums. Taking a look at these three neighborhoods, which are not seeing massive redevelopment, you’ll notice there is really no yellow line emerging from the dots. Point Breeze has a few blocks along Point Breeze Ave and some rumblings of commercial space along Passyunk Ave but nothing definitive. That Passyunk commercial space is also fairly car-centric as Passyunk widens west of broad, and was something we debated cutting out as a border. The same story occurs in Port Richmond. The yellow dots begin to coalesce on Allegheny Ave, but just barely, and its girth also puts it in the “almost border” category. West poplar is nearly commercial-less, with some transit oriented commercial happening at broad and Girard. But this is mostly fast food and it happens at the intersection of two borders.

You may have noticed we’ve compared only neighborhoods with healthy street life that lie next to ones with unhealthy street life. This being about borders we needed to take two neighborhoods undergoing very different development conditions and see what happens where they connect. Fishtown and Kensington, with hip Frankford Ave, have been booming for a while but Port Richmond has seen very little redevelopment. The 25+ foot high Lehigh Viaduct, which brings that commercial activity to a halt, is the border there.


Similarly The graduate hospital extravaganza hasn’t been able to do much past the Washington Ave border. Once our map removes the big box stores that are a car draw before they’re a pedestrian draw that Washington Ave border grows. And is enough to isolate the healthy street life of Graduate Hospital.



NoLibs and West Poplar are the same story. Two neighborhoods side by side, one developing out of control, the other has been modest. A gentle fade, then a border is the culprit here. Although the low density housing of West Poplar plays a large role as well by preventing higher density of urban living (something that tends to lead to a higher density of commercial activity).

The surges going on in the booming neighborhoods like Fishtown/Kensington isn’t likely to spread across their respective borders any time soon either. If it did the people living in Port Richmond would still have a 5 minute walk past some industrial land, under a gross tunnel and across Lehigh to get to anything Fishtown has to offer. For Port Richmond to see the same surge in development that Fishtown has it needs to develop its own variety of uses and create its own central hub of excitement. Border vacuums divide the city into smaller sections. Those sections then have to be able to stand on their own in terms of healthy street life. No leeching off your neighbor.

All in all, border vacuums have gotten a pretty bad rap, and for good reason. Unfortunately, they are an integral part of what makes the city a city. After all the city wouldn’t exist here if it weren’t for the two rivers converging. And the rail lines which were an integral part of our cities industrial past are still used to transport goods in and out.  They define the urban landscape as much as they divide it. The key is to manage borders well, to add uses in each segmented area and to bridge and connect the areas that are too small for many uses.

It is important to note that successful commercial space isn’t necessarily the thing to promote massive development, nor is massive development the thing to promote successful commercial space. It’s a little bit of both happening at the same time. The main take away is far simpler than that, (this is 101 after all). Hopefully we’ve shown that border vacuums dictate where the mixed use needs to be and that healthy urban neighborhoods cannot happen without their segmented area containing a variety of uses. That means planning for the density that will necessitate those uses, encouraging mixed use developments and live/work developments and incentivising transit oriented development while de-incentivising car oriented development. And of course, equally important to having these things is having them all in the right spot, in the right segmented area.



  1. Jake says:

    Two neighborhoods that I’m very familiar with, Brewerytown and Point Breeze, both have border vacuums separating them from another neighborhood (Fairmount and Graduate Hospital). While Brewerytown’s Girard Ave is a mixed-use corridor with light rail, Point Breeze’s is a car centric post-heavy rail corridor, Washington Ave. However, in spite of this, I see development moving at a much faster clip in Point Breeze than Brewerytown. It seems like development hasn’t even noticed Washington Ave, whereas there is much hand wringing about crossing Girard Ave from Fairmount. Based on the border vacuum hypothesis, the border of Washington Ave should have been much effort to cross, but yet this doesn’t seem to be the case. There must be something else going on here, any thoughts? Some hunches I have could be related to Point Breeze having that closer Center City feel, historical abysmal race relations in Fairmount towards Brewerytown residents, or just proximity. Thoughts?

  2. brianledder says:

    Thanks Jake. It’s good to acknowledge that border vacuums aren’t the only factor to influence development. Still I think one reason for the slow development in Brewerytown is border related. Although the Girard border is a pretty crossable one, its border to the west is Fairmount park, a river a highway… all in all pretty thick. Brewerytown’s other borders are also pretty crossable( a rail line+ Broad St.) but the neighborhoods on the other sides have even less going on than Brewerytwon. Point Breeze is neighbor to Graduate Hospital and East Passayunk, which are both doing very well. Its south and west borders are also less isolating than Fairmount park is for Brewerytown. I still think neighborhoods don’t become truly successful and stable until they develop their own core variety of uses but there is some spill over from their neighbors.

    The Non Border related Factors you mention are also important. Being closer to Center city is always good as it’s the hub of activity. But I checked google earth, and Brewerytown is only a little more than a quarter mile further away. Still maybe a quarter mile is enough. Bad race relations may sadly be a factor as well.

    My other hunch may be the number of Vacant properties, which I would think is a measure of how far the neighborhood had to go to look ripe for development. The map in this link is from 2007 but I like to start here for a hunch. Brewerytown had somewhere between 20 and 40% vacancy and Point Breeze was 8-13%. That was 7 years ago but even then Point Breeze was closer to the point where its density created a safe neighborhood. Brewerytown was further way from that to start.


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