Here are some reasons why Chicago's property grid system isn't completely perfect.

Chicago's property grid is often questioned about its imperfections. 

Historical Development

Non-Uniform Expansion: The grid didn't expand uniformly over time. Chicago grew in fits and starts, leading to irregularities where older, smaller grids joined newer ones. This mismatch can cause streets to jog or have unusual widths, disrupting seamless transitions.

1830 Original plat map of Chicago by James Thompson. From the plat map of Chicago, you can see that the Chicago River disrupted the perfect grid.

STREETS CONFIRMED TO BE FORMER INDIAN TRAILS:

Diagonal Roads: Older diagonal roads and Native American trails cut through the grid at angles, creating unusual intersection shapes and impacting block formation.

Archer Avenue: Followed a trail connecting Potawatomi villages near the Des Plaines River to Lake Michigan.

Clark Street: Part of an ancient trail following a glacial ridge, used by various tribes for centuries.

Lincoln Avenue: Traced part of an extensive trail system connecting Lake Michigan to Green Bay.

Milwaukee Avenue: Followed a well-established trail connecting Milwaukee to Chicago and beyond.

Ogden Avenue: Based on a Potawatomi trail leading from the Des Plaines River to present-day Joliet.

Ridge Boulevard: Originally known as "Indian Ridge," it followed a high-ground trail used by Potawatomi and Miami tribes.

Vincennes Avenue: Followed a trail connecting the Wabash River to Lake Michigan, used for trade and travel.

STREETS POTENTIALLY BASED ON INDIAN TRAILS:

Clybourn Avenue: Possibly followed a branch of the Milwaukee Avenue trail.

Cottage Grove Avenue: Likely followed a trail used by Potawatomi and other tribes.

Elston Avenue: It may have been part of a trail connecting the Chicago River to the Des Plaines River.

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Elston Avenue begins at 830 North Milwaukee Avenue, and ends at 6088 North Milwaukee Avenue, Chicago. 

 

Grand Avenue: It could have been part of a network of trails leading west from Chicago.

Higgins Road: Might have been based on a trail connecting the Des Plaines River to Skokie Valley.

 

Indian Boundary Road: Named for the territorial boundary established by the Treaty of St. Louis in 1816 between the Chippewa, Ottawa, and Potawatomi tribes and the United States government. 

CLICK THE MAP FOR AN ENLARGED VIEW
Map of Rogers Park and later the West Ridge communities showing Indian Boundary Road. Kenilworth Road is Touhy Avenue today. Interested in the 'LAKE' at Pratt and Kedzie? Click Here.

Sheridan Road: Potentially traced a trail used by Potawatomi and Sauk tribes.

GEOGRAPHICAL CONSTRAINTS

Lake Michigan: The lake limits eastward expansion, forcing the grid to abruptly end or bend to align with the coastline.

Chicago River and Bodies of Water: The river meanders through the city, leading to irregular block sizes and shapes where the grid has to adjust to its bends.

PRACTICAL ADJUSTMENTS AND HUMAN INTERVENTION

Railroads: Railroads required rights-of-way that often cut diagonally across the grid, causing fragmentation in the street pattern.

Expressways: Building expressways through the city involved significant alterations to the street grid, sometimes disrupting flow and continuity.

Subdivisions: Individual, smaller subdivisions within the larger community grid might use their own modified grid systems, contributing to minor irregularities.

 

Major Events: The Great Chicago Fire of 1871 destroyed large swaths of the city, and even though much of the rebuilding adhered to the grid, this event had lasting impacts on the layout in some areas.

Neighborhood Variations: Within the grid, the precise sizes of blocks and streets can vary between different neighborhoods.

DESPITE IMPERFECTIONS, THE BENEFITS OUTWEIGH THE FLAWS

While not completely without kinks, the Chicago grid still provides numerous advantages:

Easy Navigation: The grid's overall simplicity makes navigation relatively easy compared to cities with less organized street patterns.

Addressing: The grid has a logical numbering system, making addresses predictable and easy to understand.

Land Division: The grid system simplified land division for purchase and development.

Historical Narrative: The non-grid elements reflect Chicago's historical evolution and growth. 

Looking North on Pulaski Road (Crawford Avenue) towards North Avenue, Chicago, 1947.

ADDITIONAL DATA POINTS

Plank Road History in the Chicago area.

Why the North-South Chicago Streets Don't Align at North Avenue.

A Primer about the difference between a Chicago Community and a Neighborhood.

Why Chicago Changed Street Names and Address Numbers in 1909.

Why does Chicago have Multilevel Streets?

Why is Chicago's Catalpa Avenue between Western and Lincoln Avenues so wide?

Compiled by Dr. Neil Gale, Ph.D.