Here’s an online map of public radio stations across the United States. Created by Seattle-based photographer and designer Andrew Filer, it shows the broadcast range of every American public radio station—and not just NPR affiliates, but classical, pop, and other non-profit broadcasters.
The interactive version of the map is, appropriately enough, located at PublicRadioMap.com.
It’s an interesting dataset to stroll through. On the eastern seaboard, for instance, you can see the outsize reach of WHYY, the Philadelphia-based NPR affiliate, which is in orange below:
Or, at the tip of Lake Michigan, the vast primacy of my old station, WBEZ—it’s the large turquoise circle around Chicago:
(Notice, too, how big stations get in the middle of the country.)
Or the funny way in which tiny public stations sketch out the boundaries of the reservations and communities which surround New Mexico’s Carson National Forest, and other preserved land, south of Denver:
Filer took his data in part from the FCC’s frequency search. In that data, I noticed something funny: Not all the broadcasts form perfect circles. Look again at the bottom of Lake Michigan, for example, and you’ll see WBEW has notches in its broadcast. (WBEW is an intriguing institution in itself: Since 2007, it’s gone “radically public” and aired primarily “user-generated content,” submitted by website or email.)
I emailed Filer to find out more. He said that sometimes those shapes were caused by geography, such as a big mountain that obstructs a signal. But there aren’t many peaks in northern Indiana—so those shapes are likely tailored by the station to avoid interference. FM antennae, while usually omni-directional, can be adjusted so that they broadcast a weaker signal in certain directions.
“I'm not sure if these shapes are attempts to avoid interference with other public radio stations,” Filer wrote, “or just other stations on or near their same frequency (possibly a religious or community station).” Sometimes, he said, “to bring a new station on the air, a lot of crafting of these areas is required to fit within the few remaining frequency+geography combinations that are still available, especially near a major city.”
Bring up the FCC data for WBEW, and you’ll see tiny modulations in the signal strength for different directions.
Looking at the map, which is worth playing around with, I was reminded of two things. First, in our big country, the map makes clear how odd our national public broadcasting system is. It’s little more than a patchwork of independent non-profit organizations, knit together by large, themselves-independent organizations like NPR and PRI.
As I learned more, I was struck by something else: how terrestrial and material radio is. We imagine it as a kind of invisible Internet, apparent only when we turn on our receivers, but it’s actually a collection of waves, emitted by hundreds of antennae and radiated outward in carefully-crafted shapes until it hits some obstruction.
We imagine radio as distant, but, in fact, it’s all around. Radio suffuses you as you read this right now.