Washington Meridians
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The Washington meridians are four meridians that were used as
prime meridian A prime meridian is an arbitrarily chosen meridian (geography), meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. On a spheroid, a prime meridian and its anti-meridian (the 180th meridian ...
s in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
which pass through
Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...
The four that have been specified are: # through the Capitol # through the
White House The White House is the official residence and workplace of the president of the United States. Located at 1600 Pennsylvania Avenue Northwest (Washington, D.C.), NW in Washington, D.C., it has served as the residence of every U.S. president ...
# through the old Naval Observatory # through the new Naval Observatory. Their longitudes may be reported in three ways: # relative to the local vertical used by astronomic observations # relative to NAD 27 (
North American Datum The North American Datum (NAD) is the Geodetic datum#Horizontal datum, horizontal datum now used to define the Geodesy, geodetic network in North America. A datum is a formal description of the shape of the Earth along with an "anchor" point fo ...
1927), an
ellipsoid of revolution A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has circu ...
that is at mean sea level beneath triangulation station Meades Ranch, Kansas (not Earth-centered); # relative to NAD 83, an Earth-centered ellipsoid of revolution with dimensions chosen to best fit the undulating (±100 m)
geoid The geoid ( ) is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent. This surface is exte ...
(world-wide mean sea level). NAD83 longitude of the Capitol is about 1.1 arc seconds less than its NAD27 longitude; astronomic longitude there is about 4 arc seconds less than NAD83.


Capitol meridian

Pierre (Peter) Charles L'Enfant specified the first meridian in his 1791 "''Plan of the city intended for the permanent seat of the government of the United States . . .''" (see:
L'Enfant Plan The L'Enfant Plan for the city of Washington, D.C. is the urban plan developed in 1791 by Major Pierre (Peter) Charles L'Enfant for George Washington, the first president of the United States. It is regarded as a landmark in urban design and h ...
). (Shortly after L'Enfant prepared this plan, its subject received the name "City of Washington".) His plan stated near its right side that the longitude of the Congress house, now called the Capitol, was . L'Enfant's plan contained the following explanatory note:
In order to execute the above plan, Mr. Ellicott drew a true meridian line by celestial observation, which passes through the area intended for the Congress-House; this line he crossed by another line due east and west and which passes through the same area. These lines were accurately measured, and made the basis on which the whole plan was executed. He ran all the lines by a
transit instrument In astronomy, a transit instrument is a small telescope with an extremely precisely graduated mount used for the precise observation of star positions. They were previously widely used in astronomical observatories and naval observatories to m ...
, and determined the
acute angle In Euclidean geometry, an angle can refer to a number of concepts relating to the intersection of two straight lines at a point. Formally, an angle is a figure lying in a plane formed by two rays, called the '' sides'' of the angle, sharing ...
s by actual measurement, and left nothing to the uncertainty of the compass.
The longitude of the center of the Capitol's dome (completed in 1863 during the
Civil War A civil war is a war between organized groups within the same Sovereign state, state (or country). The aim of one side may be to take control of the country or a region, to achieve independence for a region, or to change government policies.J ...
) is now given by the
National Geodetic Survey The National Geodetic Survey (NGS) is a List of federal agencies in the United States, United States federal agency based in Washington, D.C. that defines and manages a national geographic coordinate system, coordinate system, providing the fou ...
as .


White House meridian

L'Enfant planned Washington around a
right triangle A right triangle or right-angled triangle, sometimes called an orthogonal triangle or rectangular triangle, is a triangle in which two sides are perpendicular, forming a right angle ( turn or 90 degrees). The side opposite to the right angle i ...
, having its 90° vertex at an equestrian statue of
George Washington George Washington (, 1799) was a Founding Fathers of the United States, Founding Father and the first president of the United States, serving from 1789 to 1797. As commander of the Continental Army, Washington led Patriot (American Revoluti ...
, its eastern vertex at the "Congress house" and its northern vertex at the President's House, now named the "White House". (This would place L'Enfant's statue north of the latitude of the Capitol.) The west side of L'Enfant's triangle forms a natural prime meridian passing through the center of the President's house. The following ten features on and near this "Washington Meridian" are listed from south to north: * The center of the
Jefferson Memorial The Jefferson Memorial is a national memorial in Washington, D.C., built in honor of Thomas Jefferson, the principal author of the United States Declaration of Independence, a central intellectual force behind the American Revolution, a fou ...
, completed on the meridian in 1943. * The ''
Jefferson Pier Jefferson Pier, Jefferson Stone, or the Jefferson Pier Stone, () is a stone in Washington, D.C. that marks the second prime meridian of the United States even though it was never officially recognized, either by presidential proclamation or by ...
''. In 1793 Secretary of State
Thomas Jefferson Thomas Jefferson (, 1743July 4, 1826) was an American Founding Fathers of the United States, Founding Father and the third president of the United States from 1801 to 1809. He was the primary author of the United States Declaration of Indepe ...
surveyed and marked with a wooden post the southwest vertex of L'Enfant's triangle, establishing the second Washington meridian, the one through the President's house. The wooden post was replaced by the ''
Jefferson Pier Jefferson Pier, Jefferson Stone, or the Jefferson Pier Stone, () is a stone in Washington, D.C. that marks the second prime meridian of the United States even though it was never officially recognized, either by presidential proclamation or by ...
'' in 1804, while Jefferson was
President of the United States The president of the United States (POTUS) is the head of state and head of government of the United States. The president directs the Federal government of the United States#Executive branch, executive branch of the Federal government of t ...
. After removal and replacement several times, it was permanently replaced in 1889 by a , 2-foot-tall, granite pier, now WNW of the center of the
Washington Monument The Washington Monument is an obelisk on the National Mall in Washington, D.C., built to commemorate George Washington, a Founding Fathers of the United States, Founding Father of the United States, victorious commander-in-chief of the Continen ...
. NGS gives its longitude as (likely error less than a centimeter). Azimuth to the Capitol is 89.98 degrees, a discrepancy of just under a meter. * The German-American Friendship Garden on the Washington Monument grounds, dedicated on November 15, 1988. * The Meridian Stone. Set In 1890 at the center of the
Ellipse In mathematics, an ellipse is a plane curve surrounding two focus (geometry), focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special ty ...
, it was intended to be on the same meridian. It is an granite post set flush with the ground. NGS gives its longitude as (likely error less than a centimeter). * The
Zero Milestone The Zero Milestone is a zero mile marker monument in Washington, D.C., erected in 1923 as the initial milestone from which all road distances in the United States would be measured. Location The monument stands just south of the White Ho ...
. Set in 1923 on the north side of the Ellipse, it was intended to be on the same meridian and to be the zero mileage point for all United States roads (but never was). It is a granite pillar about square and about tall. NGS gives its longitude as (likely error less than two centimeters). * The center of the White House. * Clark Mills' equestrian statue of President
Andrew Jackson Andrew Jackson (March 15, 1767 – June 8, 1845) was the seventh president of the United States from 1829 to 1837. Before Presidency of Andrew Jackson, his presidency, he rose to fame as a general in the U.S. Army and served in both houses ...
in Lafayette Park, erected on the meridian in 1853 (see: ''Andrew Jackson'' (Mills)). * 16th Street Northwest, which extends due north from the White House. The meridian is sometimes identified as the "16th Street Meridian" because of the location of this street. *
Meridian Hill Meridian Hill is a small urban Neighborhoods in Washington, D.C., neighborhood in Washington, D.C., located in Northwest (Washington, D.C.), Northwest D.C. Meridian Hill is often considered to be a part of the larger neighborhoods of Adams Morgan ...
. In 1804, a small freestone obelisk was placed at the crest of a hill, north of the President's House. The marker, which no longer exists, was at the northern end of 16th Street, just north of
Florida Avenue Florida Avenue is a major street in Washington, D.C. It was originally named Boundary Street, because it formed the northern boundary of the Federal City under the 1791 L'Enfant Plan. With the growth of the city beyond its original borders, B ...
, before 16th Street was extended northward about 1890, covering it up. The park along the east side of 16th Street where the obelisk once stood still bears the name Meridian Hill Park. * District of Columbia entrance marker stone (approximately east of this meridian) near Silver Spring in traffic circle (Blair Circle) at intersection of 16th Street Northwest, Eastern Avenue Northwest, N. Portal Drive Northwest and Colesville Road.


Old Naval Observatory meridian

The third meridian was defined on September 28, 1850, by
Congress A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...
: " e meridian of the observatory at Washington shall be adopted and used as the American meridian for all astronomical purposes and ... the meridian of Greenwich shall be adopted for all nautical purposes." The observatory decided that this meridian passed through the center of the original (small) dome atop the main building of the ''Old Naval Observatory'', now abandoned southwest of the corner of E and 23rd Streets in
Foggy Bottom Foggy Bottom is a neighborhood of Washington, D.C., United States, located in the city's northwest quadrant. It stretches west of the White House towards the Potomac River, north of the National Mall, east of Georgetown, south of the West ...
(north of the
Lincoln Memorial The Lincoln Memorial is a List of national memorials of the United States, U.S. national memorial honoring Abraham Lincoln, the List of presidents of the United States, 16th president of the United States, located on the western end of the Nati ...
and west of the White House). The observatory adopted for its meridian in the ''
American Ephemeris and Nautical Almanac ''The American Ephemeris and Nautical Almanac'' was published for the years 1855 to 1980, containing information necessary for astronomers, surveyors, and navigators. It was based on the original British publication, '' The Nautical Almanac and Ast ...
'' for the years 1855 to 1869 (as . In 1897, well after the observatory closed in 1892, the Coast and Geodetic Survey reported that its meridian was west of Greenwich,3618 ''Serial Set'' 254 which was quoted for the next 50 years in the list of observatories in the ''Almanac'' (as . When referred to later datums, this meridian has been variously specified as or (both presumably NAD 27). If NAD27, the latter would be which seems to be within a few meters of the actual longitude, at worst. This meridian was repealed by Congress on August 22, 1912, to allow the Greenwich meridian to become the legal prime meridian of the United States.


Western state borders

Many western states have borders that are meridians of "longitude west of Washington", that is, west of the legal 1850 meridian through the Old Naval Observatory. However, their present boundaries follow the subsequently surveyed boundary, even when inaccurately marked a few miles (kilometers) east or west of the meridian in the statute. Other western states have meridians relative to Greenwich (
Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
,
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...
,
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
) or relative to a river or lake (
Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...
,
Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...
,
Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...
,
Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...
,
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
,
Washington state Washington, officially the State of Washington, is a state in the Pacific Northwest region of the United States. It is often referred to as Washington State to distinguish it from the national capital, both named after George Washington ...
). The following meridians west of Washington are listed east to west, along with the appropriate boundary of the present state. The date of the meridian's definition is in parentheses (all in the 1860s). All states were territories of the same name when their meridians were specified except as noted. States without dates have boundaries dependent on the neighboring state with a date listed immediately above it.


New Naval Observatory meridian

The fourth meridian was through the clock room of the new Naval Observatory, northwest of the White House, at or or . The clock room is a small building at the exact center of the radius observatory grounds, whose northern entrance is at 34th Street and Massachusetts Avenue. It was used in the ''Almanac'' for the years 1898–1950 as the independent variable of time for a few tables (even though Washington's civil time since 1883 had been that of the standard time zone GMT−5 hours (75°W)).


See also

*
Washington mean time Washington Mean Time was the time at the meridian through the center of the old dome atop the main building at the old US Naval Observatory at Washington, D.C. This Washington meridian was defined on 28 September 1850 by the United States Congre ...
*
International Meridian Conference The International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States, to determine a prime meridian for international use. The conference was held at the request of President of the United State ...


Notes


References

* ** ** Note: Contains much information from book. * * Van Zandt, Franklin K. ''Boundaries of the United States and the several states'', Geological Survey Professional Paper 909 (1976) * ''American ephemeris and nautical almanac'' (Washington, DC: annual), preface and observatories


External links


The 1791 L'Enfant plan and the Mall

Map of L'Enfant's Plan

Washington Monument GPS Project
including Jefferson Pier and Zero Milestone (1.29 MB)

describing the condition of Old Naval Observatory in 1972.

listing coordinates of Jefferson Pier, Meridian Stone, and Zero Milestone (click on names for photos) {{coord, 38.895103, -77.0514428, dim:300000_region:region:US-DC_type:landmark, name=Old Naval Observatory, display=title Meridians (geography) Meridians and base lines of the United States Named meridians Prime meridians Geography of Washington, D.C.