Loudoun County, Office of Mapping and Geographic Information (OMAGI) has a seamless countywide base map geodatabase that can be used as a reference when mapping all other data. Base Map data layers include planimetric (buildings, roads, miscellaneous cultural features), environmental (hydrology, forest cover), and topographic (elevation contours and spot heights) features. Each base map feature has an update date field associated with it which shows the year when that particular feature was last updated.The countywide remapping project, conducted in two phases, was undertaken to produce the current data set. Phase I, using 2002 Virginia Base Mapping Program digital scanned imagery and Phase II, using 2004 scanned aerial photography, comprises the initial re-map effort. The initial project was completed in 2005 and now undergoes annual updates. The first annual update, Phase III, was​ derived from 2005 imagery and completed in fall 2006. The second annual update, Phase IV, was derived from 2007 imagery and completed in spring 2007. Phase V of the base map updates was completed in late 2008. Most recent updates were derived from 2024 imagery and completed in Summer 2025. Disclaimer Loudoun County is not liable for any use of or reliance upon this map or data, or any information contained herein. While reasonable efforts have been made to obtain accurate data, the County makes no warranty, expressed or implied, as to its accuracy, completeness, or fitness for use of any purpose.