The Highly Altered Areas Mask is an input of the Midwest Landscape Initiative’s (MLI) 2023 Midwest Conservation Blueprint. The Blueprint is a basemap of priority lands and waters for conservation across the Midwest consisting of over 20 social and environmental values representing diverse interests across society. For all of our input indicator layers, we use this mask to remove the most highly altered areas on the landscape from our datasets. These areas include the highest-intensity urban development, plus large roads. By removing these select areas, we help the prioritization algorithm of the Blueprint to de-prioritize pixels at the edges of the most altered areas, which in turn leads to more connected hubs in the resulting priority areas. This input layer originates from the National Land Cover Database (NLCD) and Open Street Map data. To create this layer, MLI partners, members, and staff completed the following mapping steps: projected all input data to NAD83 (2011) UTM Zone 15N, extracted all NLCD pixels classified as “developed, high intensity,” or “developed, medium intensity,” extracted large and medium roads from Open Street Map, converted all roads to a raster, and mosaicked the roads and development pixels to create a single 30m raster. Finally, to create a mask of the Midwest Conservation Blueprint extent that excluded highly altered areas, we used the Extract by Mask tool to extract all pixels which are included in Blueprint ecoregions but NOT considered to be highly altered. For full mapping details, please refer to the Midwest Conservation Blueprint 2023 Development Process document.