The obelisk on Washington’s National Mall is 554 feet, 7 and 11/32 inches tall, smaller than its historical height of 555 feet, 5 and 1/8 inches, the National Oceanic and Atmospheric Administration said in a statement.
The new measurement by NOAA’s National Geodetic Survey is based on standards of the international Council on Tall Buildings and Urban Habitats and was completed in December, the statement said.
“Today’s elevation reflects the international standards for measurement of a building’s height as well as considerable technological improvements,” said Dru Smith, NOAA’s chief geodesist.
The guidelines call for height to be measured from the level of the lowest main pedestrian entrance to the top of the building, the statement said.
The measurement of 554 feet 7 11/32 inches is accurate to within 1/32 of an inch, or 1 mm, which is the standard deviation.
The previous measurement was done when the structure honouring George Washington, the first U.S. president, was completed in 1884.
The starting point and the standard deviation for that measurement is unknown, making comparisons of the two measurements difficult, NOAA said.
The height revision arose from a request by the National Park Service, which oversees the Mall, to determine if an August 2011 earthquake had caused any settling of the Monument.
A 2012 National Geodetic Survey report showed that the Monument had settled just under 2-3/4 inches since 1901, none of it attributable to the earthquake. – Reuters