Long-term land use and land cover change, and the associated impacts, pose critical challenges to sustaining healthy communities and ecosystems. In this study, a methodology was developed to use parcel data to evaluate land use trends in southeast Arizona’s San Pedro River Watershed. Changes to parcel size are examined decade by decade, for two intervals: from 1882 to 2012, and from 1971 to 2012. Graphs are used to depict decadal parcel trends for both intervals. Parcel density maps additionally illustrate decadal trends for the 1971 to 2012 interval. The parcel density maps and graphs employ housing density categories developed by the Environmental Protection Agency’s Integrated Climate and Land Use Scenarios project. The purpose of this study is to 1) improve and describe a methodology for evaluating land use trends using parcel data; 2) display land use trends in a portion of the San Pedro Watershed using parcel data; and 3) discuss the implications of the analysis for evaluating environmental impacts with modeling tools and for assessing indirect effects as required by the National Environmental Policy Act.