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No, the National Mall wasn't built on a swamp

Changes to the area since the 1800s have helped make it less flood-prone.

WASHINGTON — They don’t call it "the swamp" for nothing -- or do they? Turns out, contrary to popular belief, a common nickname for Washington, D.C., is not based on the land upon which the National Mall was built. 


Was the National Mall built on a swamp?



No, but wetlands prone to flooding near the National Mall could create buggy, messy conditions.

RELATED: The Tidal Basin Ideas Lab is looking to save the historic space from a bleak future


The land that became the nation’s capital was selected in part because of its proximity to water, but the land for the Mall was expansive and mostly dry, according to the nonprofit “Histories of the National Mall” research project. The area was surrounded by tidal flats – expanses of land that went underwater with the rising tide. Development around the District led to erosion and clogging of drainage channels, which would sometimes cause marshy, messy, puddle-prone plots around the Mall.

The Washington, D.C., Department of Energy and Environment details efforts to make the waterways and canals around the District more efficient and friendly to visitors. In the late 1800s, the Tiber Creek was put underground - beneath today’s Constitution Avenue - and the Army Corps of Engineers began work cleaning and widening the Potomac. The material they pulled from it helped fill in hundreds of acres of flood-prone land around the National Mall. The Tidal Basin and strategic levees help prevent flooding and work to “reclaim” wetlands also helped eliminate breeding grounds for disease-carrying mosquitoes.

So while it sounds like conditions could be swampy, the Mall was not built on swamp land – just land with spots susceptible to getting soggy.

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