The ultimate app for Geography/Geology amateurs and professionals."
- Mel Martin, TUAW.com

Geograph IL is the edition of the popular GIS (geographic information system) covering the state of Illinois. It is a self-contained application (no Internet or cellular access required) that contains a vast amount of information about the geography and geology of the Prairie State. Using the iPhone's GPS, it enables you to navigate the state and get a much better understanding of your surroundings, identify geological formations, mines, rivers, school districts, etc....

This release contains 30 layers, which can be combined in any desired way:

- states outlines
- the complete geological map from USGS, with link to USGS web site for each unit
- surficial materials
- terrain elevation
- bathymetry for the southern half of lake Michigan
- zip codes
- over 2,600 named features (summits, tunnels, cliffs, bridges, etc...) with link to USGS page for each feature
- glacial limits
- U.S. congressional districts with link to representatives' web sites
- almost 2,300 mineral resources with link to USGS web site for each resource
- active mines
- old faults
- public land ownership
- hydrologic units with link to data page on EPA web site
- seismic risk
- all earthquakes in recorded history of magnitude 3.0 and above
- EPA ecological regions
- USGS quadrangles
- township and range
- urban areas
- counties with link to Census data
- hydrology
- roads and major streets
- railroad tracks
- cities and towns
- potassium/argon dates
- state plane zones
- UTM zones
- main aquifers

A number of additional layers can be downloaded from the application, including:

- state House districts with link to representatives' web sites
- state Senate districts with link to senators' web sites
- elementary school districts
- secondary school districts
- unified school districts
- boundaries of cities and villages with link to Census data
- towns
- landmark areas (parks, campgrounds, airports, etc...)
- landmark points (schols, hospitals, fire stations, etc...)
- city of Chicago alderman wards with link to aldermans' web sites
- city of Chicago precincts (all 2,605 of them)
- city of Chicago neighborhoods

Each layer contains additional information about each feature. For instance, the geology layer has a description of the unit's name, age range, rock type, and description. Each mine has a name, a commodity, a facility type, and a company name. See our web site for more information about each layer.

There have been significant improvements since the release of the sister programs covering CA, TX, NY/NJ/CT, FL, WA/OR, AZ, CO, UT, NV, NM, ID, MT, WY, MN and WI. More layers now have web links. Several bugs have been fixed.