Landfills are the most ubiquitous and expedient means of waste disposal, prevailing over any economic, logistic or political obstacles. Landfills, however, are far removed from most of society and their administration, operation and maintenance are often opaque. This research uses public participation to generate, verify and enhance existing data about the size and location of current landfills in the US while simultaneously providing users an innovative way to see and explore landfills. An online crowdsourcing tool, Landfill Hunter, was built to facilitate participation and populated with data from the Environmental Protection Agency (EPA). Participants identified a total of 729 landfills. Using this data, we estimate the area of individual landfills and calculate the cumulative land area of landfills in the US, which is approximately twice the size of New York City. In this paper, we emphasize learning outcomes that participation in this crowdsourcing initiative can generate, both online and offline, as well as creative ways that participants can visualize the resulting data.