International Date Line International Date Line The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups. The IDL is roughly based on the meridian of 180° longitude, roughly down the middle of the Pacific Ocean, and halfway around the world from the Greenwich meridian. In many places, the IDL follows
U.S. Route 180 with US 191, US 180 continues south to the town of Eagar, Arizona where the two routes enter the Apache National Forest and finally split at the town of Alpine, Arizona, roughly 4–6 miles from the Arizona-New Mexico border. After entering New Mexico from just east of Alpine, Arizona, US 180 continues south until Silver City, New Mexico. From Silver City, US 180 travels just east for roughly 4–6 miles, meeting up with New Mexico State Road 90, New Mexico State Road 15, and New Mexico State Road 152. US 180 now travels southeast for roughly to Deming, New Mexico,