A little off center from the Washington Monument, the Jefferson Pier (pronounced pie-er like a piece of apple pie) marks the second prime meridian of the United States even though it was never officially recognized, either by presidential proclamation or by a resolution or act of Congress.
The Pier is located to the west-northwest of the Washington Monument, inside the second walking path that encircles the Monument.
According to L'Enfant's "Plan of the city intended for the permanent seat of the government of the United States", there was a prominent geometric feature - a large right triangle whose hypotenuse was a wide avenue (now part of Pennsylvania Avenue, NW) connecting the "President's house" (now the White House) and the "Congress house" (now the U.S. Capitol building). To complete the triangle, a line projecting due south from the center of the President's house intersected at a right angle a line projecting due west from the center of the Congress house. The planned grand avenue became the National Mall that is now between the Capitol's grounds and the Washington Monument.
Barges used the marker as a mooring post during and after the first phase of Washington Monument's construction, which began in 1848.[15] However, that usage was not the reason that the stone was named a "pier", because the surveyor who erected it had already used that term himself. The developers of the Washington Monument originally wanted the memorial to be located at the site of the Jefferson Pier. However, concerns about the bearing capacity of the soil prevented that from occurring. The marker served as benchmark when the Monument's construction began, but later disappeared from view.
The meridian of the United States was changed to the center of the small dome of the Old Naval Observatory in 1850 and finally replaced by the Greenwich Meridian as the legal prime meridian for both boundaries and navigation in 1912.
This odd little stone is confusing to most and definitely overlooked by the massive Washington Monument which towers above. But that's okay. We know.
[Review 14290 overall, 1614 of 2020, number 101 in Washington.] read more