Greenwich Standard Time

The International Meridian Conference was held in Washington, D.C. in the United States in 1884, and 25 countries attended. The conference set the meridian that passes through the Greenwich astronomical observatory in London, England as the standard for longitude.

Because Greenwich was politically stable and had a first-class observatory, it was proposed as the site for the prime meridian at the International Geography Conference held in 1881.

Up until this point, each country had employed local times that used longitude and time in different ways. As international exchange increased, a worldwide time system was needed to prevent the confusion accompanying the development of transportation and communication.