Iowa Department of Transportation. (Jun 16, 2016). All Systems Permit (All Restricted - County Level): Iowa. State of Iowa. http://public-iowadot.opendata.arcgis.com/datasets/89f6778f3d784c0ca1d50ed456c6af80_0

Available from: https://geo.btaa.org/catalog/89f6778f3d784c0ca1d50ed456c6af80_0