Each farm field is assigned a crop using an approach that varies over the course of the year. Pre-season associations are based on crop rotation patterns. The associations are updated midway through the growing season to determine the crop type based on analysis of multi-spectral satellite data. After the season is complete the USDA releases its official Cropland Data Layer (CDL). This provides the basis for the final crop-to-field associations for growing seasons that have passed. The total area planted to a given crop within a user’s draw area is calculated by summing the field-by-field acres for all fields contained therein.