The Isthmus: A City Built on a Ribbon of Land
Near Madison, Wisconsin
Madison occupies one of the stranger pieces of urban geography in the United States. The downtown sits on an isthmus, a narrow strip of land between Lake Mendota to the north and Lake Monona to the south, about a mile wide at its widest point. It is one of only two major American cities built on an isthmus; the other is Seattle.
The isthmus was not created by human hands. About fourteen thousand years ago, the Laurentide Ice Sheet, which had buried this region under a thousand feet of ice, began retreating to the northwest. As it melted, meltwater pooled in the depressions it had carved, forming a massive glacial lake that eventually separated into the four lakes the Ho-Chunk called Teejop. The isthmus between Mendota and Monona is a remnant of the glacial moraine, a ridge of debris the glacier pushed up and left behind.
When James Duane Doty platted Madison in eighteen thirty-six, he designed the street grid to reflect its geography. Streets fan out from the Capitol Square like spokes. The main thoroughfare, Washington Avenue, aligns roughly east to west across the isthmus. John Nolen, who wrote Madison's first master city plan in nineteen-oh-nine, proposed height limits around the Capitol; after courts struck down an earlier version, a revised height law was upheld by the Wisconsin Supreme Court in nineteen twenty-three, ensuring the dome would always be visible from both lakeshore.
The result is a city that cannot sprawl in the way most American cities sprawled. Bounded by water, it grew dense in the middle and expanded outward only as bridges and roads pushed into the surrounding landscape. The water is still there, on both sides, as it has been since the glacier left and the lakes settled into their present shapes roughly ten thousand years ago.
