第二次世界大戦記念碑

Jefferson Pier, Jefferson Stone, or the Jefferson Pier Stone, in Washington, D.C., 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.

Ripps Island was an island located in the Potomac River in the northwest quadrant of Washington, D.C., in the United States. It was located at the mouth of Tiber Creek, in the vicinity of today's Constitution Gardens.