The Great Chicago Fire was a devastating blaze that swept through Chicago, Illinois, from October 8 to 10, 1871.
Claiming the lives of approximately 300 people, the fire annihilated 3.3 square miles (9 km²) of the city, destroying over 17,000 buildings and leaving more than 100,000 residents homeless.
The inferno ignited in a neighborhood southwest of the city center, though its exact cause remains uncertain. Over the years, various theories have emerged, with the most famous legend attributing the disaster to Mrs. O'Leary's cow, which supposedly knocked over a lantern during milking.
The fire also sparked another theory, one that centers on the city's peculiar blend of architectural styles and eras found within its residential neighborhoods.
Today, I'd like to explore the story of Chicago's perpetual quest for infill.
Infill development focuses on previously empty lots, abandoned buildings, unused land, or spaces between current structures within urban settings.
For urban renewal, its primary value is reducing the need for new infrastructure by leveraging existing assets, thereby saving public funds and minimizing land consumption.
As a designer, I see infill development as a unique opportunity and a challenge. It's a way to creatively transform established neighborhoods, designing new homes or mixed-use buildings that add value and vitality to the community.
But first, back to the fire and its aftermath.
The fire sparked widespread questions about urban development in the United States. At the time, Chicago's rapid growth prompted Americans to reflect on the broader impacts of industrialization, and the tragedy was seen as a critical lesson in the need for improved building practices in cities.
Frederick Law Olmsted notably pointed out that Chicago's poor construction methods were a significant issue:
Chicago had a weakness for "big things" and liked to think that it was outbuilding New York. It did a great deal of commercial advertising in its house-tops. The faults of construction as well as of art in its great showy buildings must have been numerous. Their walls were thin, and were overweighted with gross and coarse misornamentation.
Almost immediately, the city began to rewrite its fire standards, spurred by the efforts of leading insurance executives and fire-prevention reformers.
As homeowners began to rebuild and establish communities further from the city center, they reportedly adopted a dual strategy for safety.
Beyond incorporating more fire-resistant materials, it's been recounted that they would intentionally acquire two or three plots. They would then build their homes on one, deliberately leaving the adjacent lots undeveloped to create a substantial fire buffer between their property and their neighbors.
To this day, the primary width of an urban home site in Chicago is typically 25 feet. This width is standard for many residential lots in the city, especially in neighborhoods with older housing stock.
So, a 25-foot setback, which can be utilized as a garden (for example), sounds smart. Right?
It also sounds plausible as one tours Chicago's historic neighborhoods and notices newer homes of modern styles positioned next to houses that are over 100 years old.
Over time (and research), I've come to accept that the story reflects only a partial truth about post-Chicago Fire urban development, and is not entirely accurate overall.
After the fire, there was a citywide shift toward fire-resistant construction and urban reforms, but the widespread practice of routinely buying double residential lots strictly for fire separation is not extensively documented in early planning records or historical analysis.
I propose that the original "Eras Tour" began almost 100 years before Taylor Swift.
Instead, improvements focused on new building codes, which mandated brick and stone houses, wider streets, and limitations on wooden materials.
However it happened, thanks to the many infill opportunities scattered throughout, some interesting renaissances have occurred in the historic Chicago neighborhoods, which seem to happen with every generation.
Here's my theory.
As the generation that mainly built Queen Anne and Greystones in the late 1870s and 80s left their properties to family members, the empty lot next door became very attractive as a means of quick cash or expanding the family homestead.
During the 1920s and 30s, the bungalow rose to prominence as Chicago's most popular home style. Expertly adapted to the city's narrow 25-foot-wide lots and harsh weather, it swiftly became an iconic housing type.
The image above is a popular example of how Chicago’s urban landscape has changed significantly over the past century. Located in Lincoln Park on Dayton St.
In about another 50 years, after the bungalows, during the 1960s and 1970s, mid-century modern architecture began to infill the same neighborhoods. At the same time, the City of Chicago began using eminent domain to clear slums and carry out large-scale redevelopment. Many small, 25-foot-wide residential lots were taken, consolidated, or redeveloped as part of urban renewal and public housing projects.
Here we are, another 50 years or so, and it's happening once again.
The City of Chicago's Missing Middle Housing Initiative was first launched in 2023 by the Department of Planning and Development (DPD) and supported by the Chicago Architecture Center.
The initiative aims to develop quality, market-rate, small multi-unit homes such as two- to six-flats on vacant city-owned lots primarily on the South and West sides of Chicago, and includes design competitions and subsidies to encourage dense, affordable, and community-oriented housing development.
Well, one design competition, so far. Until recently.
The program initially made more than 90 lots available in North Lawndale, Chatham, South Chicago, and Morgan Park.
The second application round for the Missing Middle program opened this month with 33 City-owned lots available for redevelopment in McKinley Park, West Garfield Park, and East Garfield Park.
To facilitate development, each lot is priced at $1 (no, that's not a typo) with up to $150,000 in construction assistance available per unit.
Lots are sold to qualified minority-led housing developers in clusters, with completed homes to be made available at market rates for owner-occupants.
On August 26, 2025, the Chicago DPD announced the second round of design comp winners.
As with any government program, it has its critics.
According to Edward Keegan of the Chicago Tribune:
This is a worthwhile venture, but as the city invests, it has the responsibility to do it well. With investment comes leverage, but the city is allowing subpar design to flourish when it has the opportunity to foster better design...The mayor is presently building architectural blight, and there's no good reason for it, except it's expedient and profitable for the builders. And the cost will be high: We'll be left with overall ugliness for generations to come.
Superior Source Capital LLC - Cluster I rendering via the Chicago DPD
Outside the city's initiative, at least two local firms that participated in the competition and exhibition are moving forward with similar projects.
ParkFowler Plus is currently working with Domus Group to build 72 infill units in the Illinois Medical District. "It offers an appealing alternative to the designs that the city has approved thus far," adds Keegan.
The concept of "ugliness" may seem subjective, but as we continue to develop and expand our cities, it is important to consider the long-term impact of our actions. The decisions we make now will affect not only our immediate surroundings but also the world we leave behind for future generations.
While the Chicago Fire did drive a major transformation in building practices and urban planning, my theory of universal double-lot ownership for fire separation seems to be an exaggeration.
However, as history has shown us, even without ashes of devastation, every city provides us with opportunities to rise, rebuild, and reimagine a better future for generations to come.
Go forth and design boldly,
Steve Mickley, Executive Director
Email: steve.mickley@AIBD.org
Let's chat: AIBD.org/meetsteve
P.S. - Although the O'Learys were never officially charged with starting the fire, the story became so ingrained in local lore that Chicago's city council formally exonerated them, and the cow, in 1997.
P.P.S. - Just so you know, I spent five hours writing this email. Do you have five seconds to share it? CLICK HERE and choose your social media account.
