Today in 1884, Greenwich Mean Time (GMT) was declared the universal time at the International Meridian Conference in Washington.
Convened by President Chester Allan Arthur, the conference gathered delegates from 25 nations across the globe to select a Prime Meridian for the world in the interest of global amity and commerce.
The conference established the meridian passing through the Royal Observatory at Greenwich as the world’s Prime Meridian, and that all longitudes would be calculated both east and west from it up to 180 degrees.
GMT was also established as a standard for astronomy and for setting time zones.
From that day forward, it is from this standard that times throughout the world are calculated.