Illinois State Geological Survey Unpublished Material Version 4 (2008) raster digital data http://www.isgs.illinois.edu/ http://illinois.edu This data set consists of photo mosaic county indexes of historical black and white aerial photographs from Illinois acquired during the late 1930s and early 1940s. The original paper county indexes have been scanned and saved as TIFF format images. The images available online are MrSID files, in which the original TIFF files were compressed at a target ratio of 10:1 or 6:1 (see process steps "IMAGE COMPRESSION" below). The scale of the data varies from county to county. These data have not been geometrically corrected. These data are provided as supplemental imagery to aid in understanding the organization of the historical aerial photography collections. 1936 1941 publication date Complete As needed -91.675280 -87.483350 42.564692 36.911398 none aerial photography historical imagery black and white scanned MrSID TIFF dpi grayscale none Illinois county Midwest Metro Area Great Lakes none Pre-WWII Pre-World War II WWII World War II 1936 to 1941 1936 1937 1938 1939 1940 1941 1930s 1940s Great Depression Dust Bowl ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current. Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section. ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved.  University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section. Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage. Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section. Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data.  Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor. The data do not replace the need for detailed site-specific studies. Deette Lund Illinois State Geological Survey Assistant Supportive Scientist mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-265-5642 217-785-0211 217-244-2785 lund@isgs.illinois.edu 8:00 a.m. - 5:00 p.m., Monday-Friday Contact this individual ONLY for specific information about the use of this data set. For general questions about distribution, or availability of other data, please contact the Database Administrator listed under the Distribution_Information section. Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4 Illinois State Geological Survey Unpublished Material raster digital data Champaign, Illinois Illinois State Geological Survey Illinois State Geological Survey Unpublished Material vector digital data Champaign, Illinois Illinois State Geological Survey Illinois State Geological Survey Unpublished Material raster digital data Champaign, Illinois Illinois State Geological Survey http://www.isgs.illinois.edu http://www.vpaa.uillinois.edu/policies/web_privacy.cfm http://www.uillinois.edu/trustees/rules.cfm#sec34 http://www.fs.uiuc.edu/cam/CAM/viii/viii-1.1.html Not Applicable Not Applicable These data have not been geometrically corrected. These data have not been orthorectified. unknown Unpublished Material raster digital data Champaign, Illinois UIUC Map and Geography Library varies paper 1936 1941 publication date Not Applicable Not Applicable SCANNING METHODOLOGY: Original copies of the county indexes are located at the University of Illinois Map and Geography Library. Special permission was granted by the Library for the county index sheets to be scanned at an offsite location. The indexes were scanned on a large format Eagle 4080 scanner located at the Illinois State Geological Survey. The photo mosaic indexes were scanned at 600 dpi as grayscale images (2001-2004). In December 2004 Historic Information Gatherers, Inc.(HIG), Hopkins, Minnesota, scanned all of the remaining county index sheets (photo mosaic and line indexes that hadn't already been scanned by the ISGS) available at the UIUC Map and Geography Library (~1700 sheets). In Spring 2005 HIG provided the ISGS with digital images of the photo and line indexes. The indexes were scanned on a large format Vidar Titan Atlas P93 scanner temporarily located at the UIUC Map and Geography Library. The photo mosaic indexes were scanned at 300 dpi as indexed color images (2004). 2001-2003 & 2004 IMAGE MANIPULATION (2003-2004): The photo mosaic indexes were downsampled to 300 dpi using Adobe Photoshop. The image was also adjusted for brightness and contrast to make annotations on the image more apparent. 2003-2004 IMAGE MANIPULATION (2006-2008): The image was changed to a grayscale image using Adobe Photoshop. The image was also adjusted for brightness and contrast to make annotations on the image more apparent. 2006-2008 IMAGE COMPRESSION (2003-2004): This methodology was employed for 19 counties that were scanned. These counties include Brown, Bureau, Calhoun, Cass, Champaign, Coles, Cook, Grundy, Johnson, Knox, LaSalle, McHenry, Monroe, Peoria, St. Clair, Sangamon, Union, Vermilion and Will Counties. The original scanned files are archived in TIFF format on CD-ROM at the Illinois State Geological Survey. The files available for download have been compressed using LizardTech's GeoExpress (Solaris platform) MrSID version 1.3.1 software at a compression ratio of 10:1. 2003-2004 IMAGE COMPRESSION (2006-2007): This methodology was employed for 10 counties that were scanned. These counties include Boone, Douglas, Edwards, Gallatin, Hardin, JoDaviess, Pope, Saline, Williamson, and Winnebago Counties. A copy of the original scanned files are archived in TIFF format on CD-ROM at the Illinois State Geological Survey. The files available for download have been compressed using LizardTech's GeoExpress (Solaris platform) MrSID Version 5.0.6.1088.Bob_1055_br software at a compression ratio of 6:1. 2006-2007 IMAGE COMPRESSION (2008): This methodology was employed for 4 counties that were scanned. These counties include Alexander, Jackson, Perry and Randolph Counties. A copy of the original scanned files are archived in TIFF format on CD-ROM at the Illinois State Geological Survey. The files available for download have been compressed using LizardTech's GeoExpress (Solaris platform) MrSID Version 6.0.0.1331.Bob_1304_br software at a compression ratio of 6:1. 2008 Raster Pixel These data are not geometrically corrected. Not Applicable none none none none none Not Applicable Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois Clearinghouse Administrator mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-244-9306 217-785-0211 217-333-2830 beavrsn@isgs.illinois.edu 8:00 a.m. - 5:00 p.m., Monday-Friday Contact this individual ONLY for specific information about distribution of this data set, or availability of other data. A TIFF format file is currently available free of charge at the Illinois Natural Resources Geospatial Data Clearinghouse. Refer to the Identification_Information portion of this file for access to downloadable data and metadata. Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following: Disclaimer of Liability Disclaimer of Warranties and Accuracy of Data Disclaimer of Endorsement Disclaimer for External Links Disclaimer of Duty to Continue Provision of Data Security Choice of Law By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained. 20090416 20090416 2009 Illinois State Geological Survey Deette Lund Assistant Supportive Scientist mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-265-5642 217-785-0211 217-244-2785 lund@isgs.illinois.edu 8:00 a.m. - 5:00 p.m., Monday-Friday Contact this individual ONLY for specific information about this metadata. For general questions about distribution, or availability of other data, please contact the Database Administrator listed under the Distribution_Information section. FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time The access constraints as stated for the data apply also to the metadata. Refer to the Access Constraints section of the Identification Information section. The use constraints as stated for the data apply also to the metadata. Refer to the Use Constraints section of the Identification Information section.