Cartography · Environmental History · Archival Research & Digitization

The Empire Prairie

A multi-part mapping and archival research series · published at Practical Seed Ecology

Several of southern Wisconsin’s finest prairie remnants are described as fragments of the “Empire Prairie,” but there is very little information on precisely what that “Empire Prairie” was. Where were its borders? Why “empire”? How did it differ from the region’s countless other prairies? And what survives today? This series set out to answer those questions with narrative reporting and detailed mapping.

Map of the Empire Prairie region: the 1830s prairie extent and water features overlaid on a modern basemap of Dane and Columbia counties, Wisconsin — The 1830s extent of the Empire Prairie and its water features, digitized from Public Land Survey records and overlaid on a contemporary basemap of Dane and Columbia counties, Wisconsin.

Using the original General Land Office survey records and other archival sources, I reconstructed the prairie’s extent and rendered it as a set of original maps—then wrote the history around them.

Map of the Empire Prairie region with Ho-Chunk place names, recorded by surveyors 1829–1834 — The Empire Prairie region as recorded by U.S. surveyors and Indian agents, 1829–1834, with Ho-Chunk place names and villages.

Finding the remnants

Locating what survives of the ancient prairie took more than old maps. In addition to georeferencing and digitizing dozens of survey maps, I also digitized historic aerial photographs dating back to 1937 for each remnant of the Empire Prairie, and read them against one another to see which ground had never been plowed. Land left unbroken across every frame is the strongest candidate for original, never-tilled prairie; elsewhere the photos record the losses, as fields are turned under and woody plants creep in along the margins.

Aerial photographs of the Hauser Road prairie in 1937, 1980, and 2022 with a dashed boundary marking unplowed ground — Three representative frames—1937, 1980, and 2022. Ground left unplowed across the whole run (dashed outline) marks likely original prairie, while the same photos record plowing and woody encroachment over time.

Overlaying that photo-interpretation on the 1830s survey boundary yields a working map of what remains—intact prairie remnants, degraded remnants, and ground since restored as prairie.

Map of the Hauser Road Prairie showing prairie remnant, savanna remnant, and restored prairie against the 1830s boundary — The resulting map of the Hauser Road Prairie (Empire Prairies State Natural Area): surviving prairie, restored prairie, and the 1830s prairie boundary.

Why it matters

Knowing where these grasslands actually stood—and how their boundaries were named and remembered—sharpens the case for preserving the surviving remnants and grounds restoration in real historical geography rather than guesswork.

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