Washington, DC was established on swampland in 1791. Since that time, significant amounts of soil have been brought in or dredged from the Potomac River to create the landscape of today. As a result, many of natural features that originally existed where National Mall and Memorial Parks is now, have been paved over as the city has expanded. However, resource management in the park is still governed to some extent by the properties of urban soils and by the Potomac River. Soil characteristics influence management of plant species maintained on park land while the river, its floodplains and shoreline pose unique management issues in terms of flooding and shoreline stability.