Do you think you know the Chicago Street Grid System? Think again. And you don't have to be a French mathematician to figure it out.
Most Chicagoans know about the Chicago Street Grid System and how it works. Depending on where you are in the city, you know how far north, south, east, or west you are based on street addresses. Sometimes we'll use physical landmarks to know where we are, or we'll pull out our smartphones and use our GPS apps.
Chicago historians will tell you that either 19th-century surveyor James Thompson or 20th-century freelance urban planner Edward Brennan were the inventors of the Chicago Street Grid System. But did you know that the system is originally based on the Cartesian Coordinate System? What's that you say? Well, it's a mathematical system named after Rene Descartes, a 17th-century French mathematician, scientist, and philosopher who used algebra to solve geometric problems. In its basic form, the Cartesian Coordinate System defines the X-axis and the Y-axis in algebra. Each axis has a unit of length or distance (such as kilometers or miles). Any point within the coordinate system is measured by distance both relative to the X-axis and the Y-axis. The axis crosses at the point where the value of both X and Y is 0...that's called the origin.
As you may (or may not know), State and Madison Streets divide the north, south, east and west sides of the city. If you look at the street signs downtown at this section, State Street reads as 0E/0W (0 east and 0 west), and Madison Street reads as 0N/0S (0 north and 0 south), hence the 'origin' points. North and south along State Street is the X-axis, and east and west along Madison Street is the Y-axis. For example, if you stood on the southeast corner of State and Madison Streets in front of the old Carson, Pirie, Scott Building (now called The Sullivan Center), and started to walk north, you would notice that the address numbers go up. If you walked south from that same corner, you would find that the address numbers go down. If walked west, the numbers go down. If you walked east, the numbers will go up.
Now, let's dive into the axis' unit of length. For this one, we will refer to them as blocks and miles. One city mile is eight blocks, each block having a series of '100 numbers. You will notice that the last set of numbers in the series go up to a certain number, usually up to '60' ('40' extra numbers for extended and diagonal streets, such as Milwaukee Avenue or Stony Island Avenue). By the way, you might be wondering why diagonal streets exist and how do they fit into the grid system? Chicago's diagonal streets pre-date the grid system because they were Indian trails. Rather than planners destroy them, they incorporated them into the system.
If you know the Chicago Street Grid System and how it works, you can navigate anywhere in the city. If you are into algebra, you'd instantly 'get' the relationship between the two systems. Even if you aren't into mathematics, it's a great conversation starter, a good trivia question, and a fun fact to impress others. So now you know a little bit more about the Chicago Street Grid System and its relationship to the Cartesian Coordinate System. Use them as tools to help you get you or others around town, or as a great learning tool for your friends and family. Happy travels!
Featured Photos:
Photo 1
State and Madison Streets in Chicago, the origin points of Chicago's Street Grid System (top left). Aerial view of the Chicago Street Grid System (top right). The X and Y Axis Cartesian Coordinate System in Algebra (bottom left). The Chicago Grid System (bottom right).
Photo 2
Street light pole at northeast corner of State and Madison Streets in Chicago, the origin points of The Chicago's Street Grid System.
Photo 3
Beautiful in-ground compass rose stamp at northeast corner of State and Madison Streets pointing north, south, east and west of the city.
Photo 4
The Sullivan Center (formerly The Carson, Pirie, Scott Company Building), 1 South State Street (southeast corner of State and Madison Streets). Target, The School of the Art Institute of Chicago, and Gensler Chicago (a global design and architectural firm) are current tenants of this beautiful historic Chicago Landmark.
Photo 5
One North State Street Building (formerly The Mandel Brothers Department Store and Wieboldt's Department Store), 1 North State Street (northeast corner of State and Madison Streets). Various retail stores and business offices are now located in this historic building.
Photos 6 and 7
Two North State Street Building (formerly The Boston Department Store), 2 North State Street (northwest corner of State and Madison Streets). Walgreens and various retail stores and business offices are now home to this once successful department store building. The beautiful awning and entrance to Walgreens.
Photo 8
The Chicago Building, 7 West Madison Street (southwest corner of State and Madison Streets). The School of the Art Institute of Chicago, and various retail stores are current tenants of this historic building (listed on the National Register of Historic Places). The corner of the 3rd floor of this building houses the cornerstone of Chicago, the 0,0 origin points from where all Chicago addresses begin.
All photos by Tracy Brown (with the exception of the aerial view of the Chicago Street Grid System, the X and Y Axis Cartesian Coordinate System in Algebra, and the Chicago Street Grid System, photos by unknown, no copyright infringement is intended).
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