A Crowded Field: How we made it

Brent Jones | St. Louis Public Radio

Nov. 11, 2019

When plans for the MLS stadium started solidifying around the area along Market Street to the west of Union Station, there was a lot of talk about a “stadium district.” We got to wondering about what makes a stadium district, and if St. Louis’ three stadiums within about a mile of each other would be some of the closest in the country.

We should note right off the bat that the Edward Jones Dome, home of the St. Louis Rams until 2015, made an even closer grouping with Busch Stadium and Enterprise Center than the new MLS stadium will. This is not a new situation for St. Louis.

So, we started looking into how this new trio of St. Louis stadiums compare.

The first step was to collect data about teams and stadiums. We initially used the Wikidata query service to find information about pro sports teams and their stadiums in the five major professional sports. This was a fine starting point, and saved a lot of time, but as with most info culled from Wikipedia it needed to be checked and cleaned. The results included defunct teams as well as multiple entries for teams that have played in multiple stadiums.

There are 153 major league teams either currently playing or announced. We found 17 stadiums shared by two teams and one shared by three. The rest of the teams are their stadiums’ sole occupants. That’s 134 stadiums to keep track of. It was tough to find out which teams were planning new stadiums, which had recently moved, and, in the cases of expansion teams, which hadn’t named a location.

We took our best guess at what this landscape will look like when the St. Louis MLS team begins play in 2022. We also decided to use the planned stadiums for the Chargers and Rams, the Raiders’ Las Vegas stadium, and the Athletics’ planned park, among others.

Finally, we were only interested for this project in cities with three or more stadiums, so that lets us chop the list of cities about in half.

Now that we’d organized and checked the data, we had to do some math.

You can see more details about the process in a Python Notebook, but let’s just say working with geodata can surface all sorts of thorny issues you may not have considered before. For example: What does it mean to say “three stadiums within a mile”?

There are a number of ways to measure this! Three stadiums will form a triangle, so you could measure either the perimeter — the distance to “do a lap” of all the stadiums. Or, you could decide the distance should be how far you’d travel to visit all three — so you’d measure the shortest two sides. You might also calculate a midpoint of all three, and then measure the one farthest away. Or, you might think about the smallest circle you could draw to fit all three stadiums in.

Perhaps surprisingly, using each of these methods on the same set of data can give a different result. We decided to go with the smallest enclosing circle method. With a triangle, this means that either two of the stadiums would form the diameter of the circle and the third would lie somewhere inside it, or all three points would be on the edge of the circle.

A further wrinkle emerged in the actual wrangling of this data: location coordinates, projecting them and measuring them is difficult. Many formulas work on a flat plane, but are off — even if subtly — when applied to measurements made on the Earth’s curved surface.

Eventually, we were able to find the smallest enclosing circle around each set of stadiums to find the closest set in each city. By doing that, we narrowed the field to just 72 stadiums in 24 cities.

At this point, we evaluated our initial idea: Would St. Louis be one of the top places in the country for a stadium district? It will rank sixth, which means it’s in the top quarter. We also found the distribution of distances interesting: A handful of cities at around a mile or less, then gradual increases to about 2.5 miles, then bigger jumps above that.

Once we decided the premise was sound, we wanted to put these other stadiums in the context of St. Louis. What would Philadelphia’s or Kansas City’s stadiums look like if you dropped them into St. Louis’ city landscape but kept the distances the same?

For each of those stadiums, we calculated the distance and bearing from the center of those stadium sets. For example: In St. Louis, Enterprise Center is very close to the center of our three stadiums — it’s about 50 meters away from the center, at a bearing of 251, or west-south-west. Busch Stadium and the new MLS stadium form the diameter of the circle, each a bit over 900 meters away and at opposing bearings.

To put the other cities in a St. Louis context, we just shifted that distance and bearing to begin at St. Louis’ center point.

This yields a few interesting insights, which you can explore more fully using the map at the bottom of the project page.

For example, Minneapolis-St. Paul (ranked just above St. Louis) has two stadiums in almost exactly the same orientation as in St. Louis. The Twins’ and Vikings’ stadiums are about as far apart, and in the same direction, as Busch Stadium and the planned MLS stadium. Target Center, where the NBA’s Timberwolves play, would be in Union Station if that group was moved to St. Louis.

Denver’s arrangement is also interesting: If its three stadiums were moved to St. Louis, with the same distance and orientation, Coors Field would be where the Dome is, Pepsi Center would be across the street from Enterprise Center, and Mile High Stadium would be across Chouteau Ave. from Charleville Brewing.

Now that we had all the data settled, we needed to figure out how to best display it.

Given the difficulty of the process, we knew we wanted to explain the concept right at the top — both how we measured it, as well as the concept of putting these in a St. Louis context. We played with a few ways of doing this, but settled on scrolling captions with an animated map.

Next, to show the extents of the distances as well as to serve as a rudimentary table of contents, we show a simple bar graph of distances. This helps put St. Louis into the overall landscape and helps the reader know what to expect.

To show each city’s stadiums we’re using imagery from Google Earth, with an overlay to highlight the stadiums. We used the New York Times’ great ai2html script to create the images with text overlays and to help with responsiveness. One reason we wanted to use this imagery is that the distance only tells part of the story. While many groupings were in or near city centers, several others were not. Philadelphia was the closest grouping on our list, but the stadium complex is more than three miles from the city center. The imagery hopefully helps put that in context.

Finally, a map at the bottom shows all the stadiums in one place, in case you wanted to see what it would look like if half of North America’s major league sports teams decided to call St. Louis home.

Analysis & Design — Brent Jones

Editing — Brian Heffernan

Copyediting — MacK Korris, Bob Cronin