OK, let’s end this myth once and for all: Washington, DC was never a swamp. Only one percent of today’s city could ever be defined as swamp, and that was spread out over six different sites. That’s not to say it didn’t feel like a swamp as anyone who’s been here in August can attest. And we do have a large number of spineless, swamp like creatures (called Members of Congress). For a city built by a river, it was surprisingly swamp free.
A tour we think you'll love
The swamp story probably originates around some areas that did get wet. The worst was Tiber Creek that was turned into a canal. Because it was poorly designed, it was stagnating most of the time and it was an open sewer. It smelled horrible.
The base of Capitol Hill where the reflecting pool is today did flood regularly. The Irish neighborhood Swampoodle (pronounced swamp-puddle) now called NoMa, was not idly named. Two branches of Tiber Creek joined there and often flooded. And streams flowing out of the hills in the LeDroit Park neighborhood saturated the land there. Plus, when it rained, the dirt roads were a mess. But it was never a swamp.
For a more complete description of DC’s non-swampness visit:
https://www.washingtonpost.com/posteverything/wp/2014/08/29/no-dc-isnt-really-built-on-a-swamp/