Improving the quality of water discharged from agricultural watersheds requires comprehensive and adaptive approaches for planning and implementing conservation practices. These measures will need to consider landscape hydrology, distributions of soil types, land cover, and crop distributions in an integrated manner. The two most consistent challenges to these efforts will be consistency and reliability of data, and the capacity to translate conservation planning from watershed to farm and field scales. The translation of scale is required because, while conservation practices can be planned based on a watershed scale framework, they must be implemented by landowners in specific fields and riparian sites that are under private ownership. To support these goals, it has been necessary to develop planning approaches, high-resolution spatial datasets, and conservation practice assessment tools that will allow the agricultural and conservation communities to characterize and mitigate these challenges. The field boundary dataset represents a spatial framework for assembling and maintaining geospatial data to support conservation planning at the scale where conservation practices are implemented. This field boundaries dataset has been assembled to support field-scale agricultural conservation planning using the USDA/ARS Agricultural Conservation Planning Framework (ACPF). The original data used to create this database are the pre-2008 Farm Bill FSA common land unit (CLU) datasets. A portion of metadata found herein pertains to the USDA FSA CLU. The remaining information has been developed to reflect the repurposing of the data in its aggregated form. It is important to note that all USDA programmatic and ownership information that was associated with the original data have been removed. Beyond that, these data has been extensively edited to reflect crop-specific land use consistent with 2009 land cover as derived from 2009 NASS Crop Data Layer datasets and 2009 aerial photography, and no longer reflects discrete ownership patterns. The ACPF field boundaries feature class incorporates two additional resources that form the Illinois ACPF Land Use database. The Illinois ACPF Fields Crop History table holds the dominant land use class, derived from the NASS CDL, for individual fields from 2010 to 2020. The Illinois ACPF Land Use table hold summary land use information for individual fields for 2015 to 2020 including an assigned General Land Use (GenLU) that represent the cropping system over that period. In lieu of a data dictionary for these resources, each dataset has a FGDC-compliant metadata file using the North American ISO 19115-2003 profile in .xml format. For more information about this dataset contact David E. James at davide.james@usda.gov or dejames@iastate.edu Resources in this dataset:Resource Title: Illinois ACPF Crop History 2010-2020. File Name: IL_ACPFfields_CropHistory2010_2020.pdfResource Description: Illinois ACPF Crop History 2010-2020Resource Software Recommended: Adobe Acrobat,url: www.adobe.com Resource Title: Illinois ACPF Land Use 2015-2020. File Name: IL_ACPFfields_LandUse2015_2020.pdfResource Description: Illinois ACPF Land Use 2015-2020Resource Software Recommended: Adobe Acrobat,url: www.esri.com Resource Title: Illinois Field Boundaries 2020. File Name: IL_ACPFfields2020.pdfResource Description: Illinois Field Boundaries 2020 metadataResource Software Recommended: Adobe Acrobat,url: www.adobe.com Resource Title: Agricultural land use by field: Illinois 2010-2020. File Name: Illinois_ACPFfields2020.zipResource Description: This field boundaries dataset has been assembled to support field-scale agricultural conservation planning using the USDA/ARS Agricultural Conservation Planning Framework (ACPF).Resource Software Recommended: ESRI's ArcGIS,url: www.esri.com