Chicago's Dead Zones

🚫 A personal investigation of Chicago's cell service through a mix of maps and data research 📶

By Eve Lu

August 3, 2022

The most undisputed fact about Chicago is its prominent skyscrapers in a variety of styles, which reflect the city's history and its multicultural heritage. I was traveling to the city last week and went on a fantastic architecture boat tour with my friends. Everything around the water was pleasing on the eyes though the wind was a bit rude and I was told by my tour guide the windiest cities were actually scattered in states of Kanas and Texas instead of Illinois (doubt it but respect his knowledge:))

When you walk along the Chicago River that runs through the city, you will not only be fascinated by the shining reflection of buildings in the lake under the sunlight but then realize…ah, you just walk into a dead zone 🎉 Yes, you check your signal bar on phone, and it says:'oops, no service available.'

My cell is connected to T-Mobile service network, and it worked fairly well when I was in NYC or traveling to other major cities in the United States. So I was surprised when my cellular network was broken while I was just literally sitting in a random Starbuck on its first floor. This wasn't a one-time thing. It actually happened all the time during my five-day little trip wherever I went. I felt so lost every time I 'accidentally' stepped into a dead zone and all of sudden my google map just stopped working with me.

I remember one time I was sitting at the hotel lobby, waiting for a uber but then got a call from the driver asking me where exactly I was. I was confused and a bit irritated until I saw myself being placed right in the middle of the river on the map near the hotel, which was insanely located by the APP (but I am assuming this might be mainly related to signal blockage due to the clustered buildings around). I also experienced a few awkward moments when I was trying to show my online tickets but with the page forever loading just because of the weak and inconsistent cellular network.

Though after everything I still had a really great time there, I'm wondering if those places I went to are covered by 5G or 4G network and how many cell towers are there?

I completly lost connection to the real world when I was at 360 Chicago Observation Deck but...somehow it is understandable because the observatory is on the 94th floor...(already in the air)

Sitting on the thrid floor to have a delicated Tiramisu but with a poor signal when I tried to post an instory for my cake!!!

360 Chicago


Reserve Roastery

Navy Pier

Signal strength is of average here

Royal Sonesta Hotel

I was totally isolated here...feeling so embrassed when the online tickets’QR were forever loading and I ended up taking screenshots of all the tickets outside the planetarium and sneakily came back.

Where I stayed and where GPS had put me in the middle of the river nearby while waiting for a uber...


Pancakes and Cafe

I was here for a fancy brunch but had been put on the waitlist for like 30 minutes. During that half an hour, I was able to get online on my phone, but the signal wasn’t that strong enough so I had to refresh the pages or app every five minutes.

Signal strength was good at some points but I haven’t checked every corner of the museum, so...

Field Museum

Adler Planetarium

The map shows where I've been and how I generally felt about the cell's signal there. Though I know there might be tons of reasons to affect cellular signal strength, major explanations can be listed as below:

  • 5G or 4G coverage network provided by your mobile carrier;
  • Your distance from a cell tower.
  • And, thick material like concrete and steel that stop signal from penetrating a building (even glass is able to impair the singal strength!!);

  • Am I covered by 5G or 4G network?

    On T-mobile's official website, click on 5G & 4G Coverage map , then you will get an highly saturated mulberry map which says their 5G (or at least 4G LTE) network is touching almost every corner of the country and of course 🧐 is including Chicago as a place with full 5G Ultra Capacity.

    A screenshot of T-mobile's 5G/4G coverage map in Chicago

    A screenshot of T-mobile's 5G/4G coverage map in Chicago seems like 5G Ultra Capacity actually means 'oops human, you won't be able to connect whenever and wherever you can even if our map shows Chicago is extremely red.'

    Note: I use T-mobile so I did a research on their service coverage map but you can easily find your mobile carrier's availability by typing something like "xxx 5G coverage map"💡

    So, how many cell towers are nearby?

    Data by Antenna Search, Chicago has 42 registered cell towers in town. Below displays where those registered towers are scattered:

    How Chicago's 42 registered cell towers are distrubuted ・ Source by Antenna Search

    Of 42 cell towers in total, 11 of them are owned by T-mobile. When you zoom in a little bit more, you will notice most of t-mobile towers are gathering in downtown area, however, being submerged by hundreds of high-rises at the same time.

    Normally, your phones allow you to be 1-2 miles away from a cell tower. If we just look at the data, Chicagoans shouldn't have worry about their cell-phone signal strength at all?!🤔 (in case you want to know, Chicago actually has more than 430 non-registered cell towers and over 5000 antennas within a three mile radius of the city).

    But, why am I still being blocked by the city? it must have something to do with the skycrapers🌃!!!

    It seems like cell network coverage is doing its excellent job and meanwhile the city has enough cell towers to back it up. In that case, I am assuming the major reason why I was being blocked might be related to a dense cluster of these outstanding skycrapers in the city.

    A screenshot of Chicago

    Current building footprints in Chicago ・ Source by Chicago Data Portal; Map supported by QGIS

    When you look at the map, the building footprints are compacted so closely and almost the entire city is loaded with thousands of constructed landmark buildings of varying styles. Dead zones can occur under various situations, however especially when large objects come between you and the cell tower, explained by the Federal Communications Commission (FCC).

    Additionally, the materials used to build the high-rises also make a big difference in whether your cell reception would get killed or not. Glass is said to refracts the signal causing a loss of about -4dB (special designed glass for better privacy even makes it worse). Also, the more layers of materials, the more signal is block. Buildings out of concrete or cement will cause a loss of between -10dB and -20dB, which contributes to the major reason why your cell often has an extremely poor signal strength when you are at most underground places.

    Well, I guess...this is probably the 'biggest' reason 🔍(?) why I was being blocked whenever and wherever I went... but I am not excluding other potential possiblities and will keep exploring 👀.