First Lesson
James Thompson's original plat map that established the rigid block system over the Chicago River's wild geography.
Picture a wild, wet grassland where a river bends lazily into a massive lake. In the early 1800s, the place we call Chicago was a swampy marshland dominated by wild garlic. It was a difficult place to build, but it was also a highly strategic spot. To control the water route between the Great Lakes and the Mississippi River valley, the United States army built Fort Dearborn here in 1803. This log fortress stood on a small hill of dry ground on the south bank of the Chicago River, watching over a landscape of mud, water, and sand dunes.
The fort was not built to start a city, but to guard a vital portage. Native peoples and fur traders had used this muddy shortcut for centuries to move their canoes between the river and the lake. When the United States government decided to build a massive canal to permanently connect these waterways, they needed to fund the project. In 1830, they appointed a group of officials called the Canal Commissioners to map out and sell the surrounding land to raise the necessary money.
To sell the muddy wilderness quickly, the commissioners hired a surveyor named James Thompson. He did not design a town that fit the curves of the river or the wet shape of the land. Instead, he laid down a rigid, paper-flat checkerboard pattern of square blocks and straight streets. This layout is known as a gridiron plan. Thompson's map covered just three-eighths of a square mile, stretching from modern-day State Street to Halsted Street, and Madison Street to Kinzie Street. It completely ignored the swampy reality of the ground beneath it.
The grid was a mathematical net thrown over a wild, watery landscape, turning a swamp into a set of neat, tradeable boxes.— Harold M. Mayer, The Growth of Chicago
This grid was highly practical for land speculation, which is the act of buying land cheaply in the hope of selling it later for a quick profit. Straight lines and equal, rectangular lots made it incredibly easy for buyers in distant cities like New York to purchase land sight unseen. They did not need to visit the muddy banks of the river; they only needed to look at Thompson's neat paper grid. This simple map instantly turned wild nature into a highly liquid financial asset, setting the stage for a massive real estate boom.
Cronon, William. Nature's Metropolis: Chicago and the Great West. W. W. Norton & Company, 1991. — This landmark book explains how the transformation of Chicago's landscape was driven by the demands of eastern financial markets.
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