Washington, D.C., was established as the “permanent seat of the Federal Government” by the passage of the Residence Act in 1790. This act allowed President George Washington to select the site for the new city anywhere along the banks of the Potomac River between its junction with the Shenandoah River, near present day Harpers Ferry, West Virginia, and its junction with the Eastern Branch or Anacostia River, just below the current location of Washington, DC.
The area demarcated for the new city was a blank slate and President Washington selected Major Pierre Charles L’Enfant (1754-1825) to create a design for it. The map below, published in 1794, reflects L’Enfant’s vision for the new city with a few improvements attributed to Andrew Ellicott (1754-1820).
The detail below shows the Potomac River, the mouth of Tiber Creek, and the United States Mall as laid out by L’Enfant and Ellicott. Running along the Mall, as we know it today, was a creek that led westward from roughly the current site of Union Station to the Tidal Basin and, ultimately, to the Potomac River. What many Washingtonians may not realize is that both L’Enfant’s original design, and Ellicott’s improvement incorporated canals to facilitate the shipment of goods and construction materials to build the new city.
In addition to the canal running past the White House, there were grand plans for a university on the west end of the Mall and a turning basin for the canal at the base of Capitol Hill. The proposed University resembles the original campus of the University of Virginia!
So why the canal? It was simply a time saving measure. The sandstone blocks that were used in constructing the White House, the United States Capitol, and other government buildings in the new city, were quarried in Aquia, Virginia, located approximately 45 miles south of Washington, D.C. The stone was transported up the Potomac River and, via the canal, to the future sites of government buildings along the Mall.
The canal eventually outlived its usefulness and, as the city grew, its popularity as a means of transporting cargo waned. By the late 1870’s the canal was virtually an open sewer and the decision was made to fill it in.
Source – For more click here