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Witness Trees of Illinois

FIND TREES THAT HELPED MAP ILLINOIS!Click here to check out our interactive Witness Bearing Tree Map!
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? All you need is a smartphone to help us find out. You don’t need to know anything about trees or maps to become part of this living history project.
In this project, we're asking Illinois residents to visit the sites of bearing trees located on their property or on public property and record information about any remaining witness trees left in Illinois, using the the map below. Note: Please do not enter private property unless you have permission or hike off maintained trails!)
The Public Land Surveys of the 1800s

Early in the 19th century, surveyors operating under the authority of the U. S. Surveyor General began surveying lands that would eventually comprise the State of Illinois. The surveyors moved across the state laying out a rectangular grid system, known as the Public Land Survey System (PLS or PLSS).
The surveyors kept notes about the quality of the landscape and other “remarkable and permanent things.” Where possible, they also identified 3-4 “bearing trees” at each corner and mid-point on the grid so that the spot could be re-located in the future (in areas with no trees, they would construct mounds of soil as markers). For each tree, they recorded its common name, location, and size. The 
surveyors also recorded similar information for any tree that fell directly on the line of their survey grid (called “line trees”). These plat maps and field notebooks contain a wealth of information about what the landscape was like before settlers came into the state - and the majority of trees described were oak species!
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!
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.