We developed a composite land cover approach for use in the GCPO LCC ecological assessment of upland hardwood woodlands and forests. These datasets reflect the upland hardwood “mask” that represents the composite of 3 or 4 datasets, from which the remaining landscape endpoints defined in the LCC Integrated Science Agenda will be evaluated. The mask indicates where on the landscape we estimate upland hardwood woodlands and forests to be found in any condition. We first resampled 30 m 2011 GAP ecological systems land cover and Florida Cooperative Land Cover version 3.1, as well as 10 m Texas and Oklahoma Ecological Systems Mapping land cover data to 250 m using a nearest neighbor algorithm. The assessment was conducted at a 250 m spatial resolution to allow for use of U.S. Forest Service Forest Inventory and Analysis Program (FIA) imputed data to assess several landscape endpoints related to forest structure. To proceed with the mask we reclassified each 250 m land cover layer to extract the selected woodland and forest classes, and created a binary (1,0) layer for each woodland and forest layer. These data were clipped to a 10 km buffer around the GCPO boundary. For upland hardwood woodlands we then mosaiced three binary datasets together, taking the Oklahoma and Texas data as primary over the remaining GAP data for the rest of the GCPO geography. The result was a binary raster layer of upland hardwood woodland that represented state-derived woodland classes for Oklahoma and Texas, and GAP woodland cover for the remaining states in the GCPO. For upland hardwood forests, we mosaiced four binary datasets together, taking the Florida, Oklahoma, and Texas data as primary over the remaining GAP data for the GCPO. This resulted in a separate binary layer for upland hardwood forest similar to that of woodland. These became the woodland and forests “masks” summarized below and used in the remainder of the assessment. We then used the Tabulate Area tool in ArcGIS Spatial Analyst to calculate acreage of woodland and forest within each HUC12 watershed, and then calculated the proportion of each watershed comprised of woodland and forest. The upland hardwood mask serves as the baseline layer within which endpoints of tree density, basal area, down wood, etc.. are evaluated as part of the assessment. This information on current status of upland woods will be compiled to serve as one of four foundational elements of the GCPO LCC conservation blueprint.