Has the Washington Monument shrunk? The only observable height change was the pyramid-shaped tip, which has been rounded off over time, possibly by frequent lightning strikes that melted the aluminum tip (Reuters)
Has the Washington Monument shrunk?

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Government surveyors have determined a height for the Washington Monument. It's nearly 10 inches shorter than what has been thought for more than 130 years.

The measurement puts the monument at 554 feet, 7 and eleven-thirty-seconds of an inch. That is measured from the floor of the main entrance to the top. Ever since the stone obelisk was completed in 1884, however, the historic height has been recorded at 555 feet, 5 and 1/8 inches. It's a number circulated for decades on tours of the capital and in civics classes.

The monument honors the nation's first president.

So could this be a case of an incredible shrinking monument? Has it sunk into the ground more than previously thought?

No, not even close, said the chief scientist at the National Geodetic Survey, which conducted the measurement with accuracy to within one millimeter.

Modern international standards from the Council of Tall Buildings and Urban Habitat an official guideline for building measurements call for a different base point than what was likely used in the 1880s, said Dru Smith, chief geodesist with the National Geodetic Survey. The standard measures from the lowest open-air pedestrian entrance to the building.

"The building didn't change height because of anything. It is just where you start from," Smith said.

The original measurement was conducted in 1884 by Lt. Col. Thomas Casey. He is believed to have used four brass markers as a base for measurement. Those markers remain in place. They are 9 inches below ground off each corner of the monument. It's possible the markers were at ground level in the past. A new plaza was installed around the monument more recently.

"It's clear that what was ground level has changed over the years," Smith said.

Measurements from the brass markers to the top in 1999 and 2014 essentially reconfirmed the original measurement. They showed the 1884 measurement was done with "incredible accuracy."

The only observable height change was the pyramid-shaped tip, which had been rounded off over time. Surveyors in 1934 also noticed the peak had been rounded. They believed it was due to frequent lightning strikes. The strikes had melted the aluminum tip.

"Well, this time around, we took very careful measurements," Smith said. "We were able to determine about 3/8 of an inch had been melted off from the very top."

That means the original 1884 measurement, completed with much less sophisticated equipment, was within 3/4 of an inch of the findings from the newest survey, using the original brass markers as a base point.

"It's remarkable, quite honestly, that they had the ability to get such an accurate measurement back in that time," Smith said.

The monument was completed in 1884. It was the world's tallest structure until 1889 when the Eiffel Tower was built. It remains by far the tallest structure in the nation's capital. The city strictly restricts building heights. Most buildings are shorter than the U.S. Capitol dome, which rises 288 feet.

The new survey was conducted while the monument was wrapped in scaffolding. The restoration work is being done because of a 2011 earthquake. Earlier survey results showed the monument did not sink further into the ground as a result of the 5.8-magnitude earthquake. The monument was built on land that used to be underwater. It has sunk about 2.2 inches since 1901.

The National Park Service is the caretaker of the monument. The service has no intention of changing its brochures or description of the height to reflect the new numbers.

"We'll still use the historic height rather than the architectural height, since they're measured from different places," said spokeswoman Jenny Anzelmo-Sarles.

The extensive survey will give the Park Service new data as a baseline. The service will track any changes in the monument's height, tilt or compression in the future.

"I think we can all agree the significance of the Washington Monument is really far greater than the architectural qualities or even its height," said Mike Commisso. He is a cultural resources specialist for the National Mall.

Critical thinking challenge: What changed to effect the official height of the monument?

Assigned 91 times

  • aidan2459
    2/20/2015 - 08:24 p.m.

    This article is about the Washington monument shrinking. They said in the past 130 years it has shrunk. it was shortened by 10 inch.the monument is 154 feet.it was ab pout 156. in my opinion it doesn't mad er

  • Eric0221-YYCA
    2/20/2015 - 08:39 p.m.

    I think that it is weird for the monument to start shrinking down the ground level because some people think that it is shrinking all because of the 2011 earthquake but the shrinking thing on the Washington monument is because of a lightning strike. Well if the lightning strike could cause the monument to shrink because a single lightning strike is hotter than the sun's UV ray, the lightning will like melt the whole top off that will seem strange if some people saw that they is no pyramid-top on the tip of the Washington monument. If the lightning strikes the tip of the monument that is hotter than the sun, that would kind of melt the whole monument down if the lightning is hotter than before.
    Critical thinking challenge: What changed to effect the official height of the monument?
    Answer: The effect of the official height of the monument is because of the lightning striking it if the strom comes to Washington D.C.

  • LucasH-3
    2/21/2015 - 02:54 a.m.

    People have noticed a change to the Washington Monument lately. Over the past 130 years, it has shrunk about ten inches. It is now about 555 feet above land. It has sunk about 2.2 inches since 1901 and is bound to continue to shrink.

  • justinn-DiB
    2/22/2015 - 06:44 p.m.

    I also think that the monument could have eroded over time even though it is made out of metal. The Earth also doesn't stay flat forever.

  • Kaylab-5
    2/22/2015 - 08:30 p.m.

    This article is about how the Washington Monument has shrunk since 1884, when it was built. The monument was first measured at 555' 5 1/8". Today it has been measured at 554' 7 11/32". I find this very interesting. I woder what could have caused this.

  • josiahn-DiB
    2/22/2015 - 08:57 p.m.

    i think their making a big deal out of nothing if the monument did shrink its not that obvious.
    i think it would be a bigger problem if it started to fall.

  • cheyennec-Koc
    2/22/2015 - 11:15 p.m.

    I think that since its been there for 130 years, some of the top has withered away. Many mountains have withered away through the years, it's just nature.

  • LaurelM-4
    2/22/2015 - 11:56 p.m.

    The Washington Monument is now 10 inches shorter. The monument is 554 feet and 11/32 of an inch tall. The reason for the height difference is the changing of the ground level and lightning strikes that melted of the aluminum tip. Now the monument has a rounded tip instead of a pointed tip. This article was very interesting to me. It's cool to see how things change over time.

  • MailanN-4
    2/23/2015 - 12:57 a.m.

    This article is very interesting because I know that the Washington Monument didn't just shrink but something scientifically had to happen and I would have thought in the beginning that it would've have just gone deeper into the ground but what actually caused it to be shorter
    And smaller is because of the erosion from the lightning and rain and natural things.

  • paigek-Koc
    2/23/2015 - 02:27 a.m.

    I think thats crazy how they think it could of shrunk. I dont know how rise could be possible but it's kinda cool at the same time.

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