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
Interstate 180 (Pennsylvania) signage, concurrent along these routes. At exit 27A, US 15 leaves the overlap running south across the Carl E. Stotz Memorial Little League Bridge and I-180 continues eastward, still concurrent with US 220 northbound. From there, I-180 runs along the West Branch Susquehanna River until the highway reaches the eastern suburbs of Williamsport, where US 220 leaves the Interstate via exit 15. From US 220 to the eastern terminus, I-180 is aligned north–south, though the highway is signed east–west. I-180 terminates interchanging Interstate 80 and the freeway continues as Pennsylvania Route 147. Interstate 180 (Pennsylvania) Interstate 180 (abbreviated I-180) is