Illinois Archaeological Predictive Model

Illinois Archaeological Predictive Model (IAPM)

An archaeological service from the Prairie Research Institute to the citizens of Illinois

The Illinois Archaeological Predictive Model (IAPM) is a GIS-based tool developed by the Illinois State Archaeological Survey (ISAS), part of the Prairie Research Institute at the University of Illinois at Urbana-Champaign. The model builds on over a century of archaeological work in Illinois, and considers the known locations of prehistoric Native American sites, landforms that lack archaeological sites, and other environmental and geophysical variables such as elevation, distance to rivers and streams, and native vegetation. Data sampled from these locations are analyzed via GIS (Geographic Information Systems) using multilevel Bayesian logistic regression statistics to predict the probability of encountering an archaeological site in every two acre square (90 x 90 meter cells) across the state.

ISAS and other interested stakeholders use the IAPM to help protect, preserve, and assess the potential impact to irreplaceable and non-renewable archaeological resources within the context of Illinois' need to encourage and promote sustainable development. Using the IAPM helps archaeologists prioritize time and resources during surveys, and allows us to make recommendations that prevent or mitigate impacts to the archaeological record. It also has the potential to enable ordinary citizens, managers, developers, and preservationists to become proactive planners when it comes to the archaeological resources of Illinois.

Interested? Go to or click on the image below to explore the Illinois Archaeological Predictive Model.

The Illinois Archaeological Predictive Model (IAPM) predicts the probabiilty of encountering an archaeological site in each 90x90 m cell across the state. Probability values are on a continuous scale between 0.0 (blue) and 1.0 (red).

  1. Navigate to your area of interest by clicking My Location, searching for an address or place, or entering a set of coordinates.
  2. Use the Layer List to turn reference layers or the site probability layer on/off.
  3. Use the Add Data button to insert layers from ArcGIS Online, an URL, or an external file (zipped shp, csv, kml, gpx, or GeoJSON).
  4. Click the Legend to see symbology for all active layers.
  5. You can also use the Measurement or Draw tools to explore areas and mark features of interest.
  6. The Print button automatically generates a map layout that includes a title, scale bar, legend, and copyright info. After selecting page layout and export format, click Print, then click your file in the list to download.

For help using the IAPM viewer, email the Illinois State Archaeological Survey at

By using the IAPM viewer, you agree to the Terms of Use in the Data Use License Agreement.