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Witness Trees of Illinois

We’re looking for a special kind of witness tree: the historic trees that helped map the state of Illinois.
In the early 1800s, surveyors used “bearing trees,” many of them oaks, as landmarks. How many are still with us, as living witnesses to our history? We want to know: How many of these trees survived?
You can help us find out. All you need is a smartphone. You don’t need to know anything about trees or maps to become part of this living history project.
We're asking Illinois residents to visit the sites of bearing trees on their property or on public property and record information about any remaining bearing trees left and, if not, what is there now.
Want to look for bearing trees near you? Click here to get started!
Note: Please do not enter private property unless you have permission nor hike off maintained trails!)
Want to know more about historic Land Surveys in Illinois? Click here.
Why do we hope to find these trees? Find out here.
Where to Look for Bearing Trees?
The map below includes the locations of the original bearing trees and line trees as recorded by the surveyors in the 1800s. Click on a point to see more information about the species and the size as noted by the surveyor. There is also a place to record your observations, including whether or not the tree is still there- You can even upload photos! Most points on the map are accurate to about 15 feet, so be sure to look nearby for very large trees that might fit the bill.
More data points will be added over time- check back in 6 months!

Project Partners:
This project is a collaboration of The Morton Arboretum, The Field Museum, University of Notre Dame and the PalEON Project, and US Geological Survey.
The PLS data for Northeastern Illinois was transcribed by Marlin Bowles and Jenny McBride of The Morton Arboretum.
All other PLS data in Illinois was transcribed by 37 individuals from Jason McLachlan's lab at the University of Notre Dame as part of the PalEON Project ( This work was funded by the National Science Foundation grant DEB 1241874 and the Upper Midwest and Great Lakes Landscape Conservation Cooperative.