Although people have been tracking time for centuries, it wasn’t until the discovery of the New World that scientists and cartographers realized the need for a standardized approach to measuring time across multiple longitudes. Back then, each country used its own method, but as England continued to rule the oceans, its approach became the global standard. Choosing the observatory at Greenwich, England, as the Prime Meridian, making it 0 degrees longitude, the planet was divided into 360 degrees, with the International Date Line located at 180 degrees. Established time zones didn’t come about until the late 19th century, when railroads needed a uniform approach to time in order to create usable train schedules. Sir Sandford Fleming, a Scottish engineer who worked for the Canadian Pacific Railway, was the first person to propose the creation of international standard time zones while the continental United States was divided into the four time zones we still use today in 1883.