Access DOQ files for Illinois by County

Illinois DOQ data is available by quarter-quadrangle in UTM Zones 15 or 16, NAD83. Each .zip file includes <filename>.sid and <filename>.sdw, which are the image file and a georeferencing file.

Adams	Alexander	Bond	Boone	Brown	Bureau	Calhoun
Carroll	Cass	Champaign	Christian	Clark	Clay	Clinton
Coles	Cook	Crawford	Cumberland	De Kalb	Dewitt	Douglas
DuPage	Edgar	Edwards	Effingham	Fayette	Ford	Franklin
Fulton	Gallatin	Greene	Grundy	Hamilton	Hancock	Hardin
Henderson	Henry	Iroquois	Jackson	Jasper	Jefferson	Jersey
Jodaviess	Johnson	Kane	Kankakee	Kendall	Knox	Lake
Lasalle	Lawrence	Lee	Livingston	Logan	Macon	Macoupin
Madison	Marion	Marshall	Mason	Massac	McDonough	McHenry
McLean	Menard	Mercer	Monroe	Montgomery	Morgan	Moultrie
Ogle	Peoria	Perry	Piatt	Pike	Pope	Pulaski
Putnam	Randolph	Richland	Rock Island	Saline	Sangamon	Schuyler
Scott	Shelby	Stark	St. Clair	Stephenson	Tazewell	Union
Vermilion	Wabash	Warren	Washington	Wayne	White	Whiteside
Will	Williamson	Winnebago	Woodford