International date line: The International Date Line

The International Date Line (IDL) is an imaginary line running through the Pacific Ocean that separates one calendar day from the next. It’s located around the 180° longitude, directly opposite the Prime Meridian. Learn what the international date line is, how it was established in 1884, and how it affects time and dates around the world. See how the date line zigzags around political borders and crosses the Pacific Ocean. The International Date Line (IDL) is an imaginary line that runs from the North to the South Pole and separates two calendar days. Learn about the line that separates one calendar day from the next, and how it affects the date and time around the world. See the geography, history, and cartographic conventions of the IDL, and some facts and examples of its impact.