These files represent geographies underlying the air quality conformity analysis modeling. They were developed by the Chicago Metropolitan Agency for Planning and cover the modeled region, including portions of Wisconsin, Illinois and Indiana. IMPORTANT NOTE: 2017 Trip Generation and Traffic Analysis Zone shapefiles are to be used with 2019 Q1 and later conformity analyses; 2009 shapefiles are to be used with 2018 Q3 and earlier conformity analyses.