Ever stopped to ponder what this unassuming spot near 24th and H Streets represents? This is the American Meridian Monument. It marks a line that once held significant importance in the United States.
Before 1850 countries used different meridians for longitude. There was no universal agreement like with latitude and the Equator. Prime meridians existed in Greenwich Paris and Rome among other European cities. American navigators often used the French meridian at Paris or the British one at Greenwich.
In 1850 the United States established its own American Meridian. It ran along 24th Street. The federal government used this line for measuring distances on land. It helped survey the West coordinate clocks and mark the start of new days.
Few navigators adopted the American Meridian. They were used to charts based on Paris or London. The United States continued using the Greenwich Meridian for longitude at sea. Land surveyors welcomed measuring from the new American Meridian. It was easier than using a line across the ocean. Surveyors and mapmakers measured westward. The square boundaries of Western states used round numbers from the American Meridian.
Oregon was the first state to use the American Meridian in 1859. Its southeastern border was exactly 42 degrees west of it. Colorado Territory followed in 1861. Its eastern and western borders used the meridian. Wyoming’s eastern border Arizona’s location and the Utah-Nevada border were all measured from this line.
Congress officially abandoned the American Meridian in 1912. They accepted the Greenwich Meridian as the international standard. The American Meridian became history. Today this monument is one of three reminders in D.C. It shows the evolution of cartography in the United States.
Meridian Hill Park is another reminder. It was named for a stone obelisk erected along the original prime meridian in 1804. The stone is gone but the park remains. The Zero Milestone south of the White House is the third remnant. It marks the pre-Greenwich Meridian age.
Longitude is crucial. Establishing a prime meridian was challenging. Unlike latitude there’s no natural choice. Standards evolved with meridians in various European cities. Thomas Jefferson set the first American Meridian through the Executive Mansion in 1793.
In 1850 the American Meridian moved to 24th Street at the Naval Observatory site. It remained until 1884. Then the United States adopted the Greenwich Standard by international treaty. A local point allowed better continuity.
The American Meridian at Washington determined state borders created or altered between 1850 and 1912. Surveyors primarily used it.
So remember as you stand here at the American Meridian Monument you are at a spot that was once considered the center of the world. It played a role in shaping the United States. It is a tangible link to a time when America charted its own course. A time when the nation defined its place on the map.