At the start of the 19th century there was no universally agreed point from which to measure longitude, and this caused problems both for identifying geographical locations and measuring time.
Although latitude was able to be measured from the equator, variations in geographical longitude meant that different towns and cities had slightly differing time standards since the vast majority of settlements around the world observed local mean solar time.
The arrival of the railways in the mid-19th century increased the need for a standardised time across the network, since local time would differ in all the towns the train visited.
In Great Britain, Greenwich Mean Time was first adopted by the Great Western Railway and in 1870 Charles F. Dowd proposed a unified time system for North America based on the Washington Meridian.
Following further developments by Sandford Fleming and Cleveland Abbe, who proposed time zones for the entire world, U.S. President Chester Arthur requested a conference to discuss the choice of ‘a meridian to be employed as a common zero of longitude and standard of time reckoning throughout the world’.
41 delegates from 26 nations travelled to Washington, D.C. where the International Meridian Conference began on 1 October 1884.
Three weeks later, on 22 October, they adopted a series of resolutions that resulted in the Greenwich Meridian becoming the international standard for zero degrees longitude, ensuring continuity with most existing nautical charts.
Nevertheless the resolution was not accepted unanimously since San Domingo voted against, and both France and Brazil abstained.
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