and support multiple types of web based GIS applications. In addition to downloading data and creating map services, many GIS clearinghouses also have created web based GIS applications. The applications available through PASDA include the Pennsylvania Atlas—a data visualization and download app, the Pennsylvania Imagery Navigator—a data visualization, search and retrieval app for imagery and LIDAR, and the Pennsylvania Mine Map Atlas. The Pennsylvania Mine Map Atlas is a joint project of PASDA and the Pennsylvania Department of Environmental Protection. This Mine Map Atlas provides access to thousands of scanned, georeferenced underground mine maps in the Commonwealth of Pennsylvania. It allows users to view their homes and see if any mines are beneath those homes. The purpose of this effort is to identify houses and other structures at risk of mine subsidence, ground movement caused by the collapse of old, abandoned mines. The final number of mine maps that will be provided through this application is expected to near 100,000 individual maps. Related Initiatives & Users PASDA has participated in numerous national and international level initiatives since its beginnings in 1996. PASDA was an original member of the ESRI Geography Network and ESRI's ArcGIS.com. In addition, PASDA metadata is harvested by multiple data portals including Geospatial One Stop, Data.gov, and the National Biological Information Infrastructure. PASDA is an open data portal—meaning that is provides open, free, unrestricted access to data in multiple formats. PASDA provides data storage, data access and retrieval, and metadata services free of charge to its data providers because access to data drives economic development, conservation efforts, and collaboration. The data made available through PASDA is provided by data partners to encourage the widespread sharing of geospatial data, eliminate the creation of redundant data sets, and to further build an inventory (through the development and hosting of metadata) of available data relevant to the Commonwealth. The PASDA user base is extensive. Users come from a broad spectrum of organizations and backgrounds, from teachers and citizens to businesses and government agencies—PASDA provides free access to data, applications, and customization tools to meet the needs of every user. PASDA saw a dramatic increase of use in almost every sector driven in part by factors such as Marcellus Shale exploration, environmental conservation, economic development initiatives, expanded use of geospatial data in universities, non profits, and the private sector, and the increased interest from average citizens who are able to access