A particular, hypothetical line on the Earth separating neighbouring regions in which the civil dates differ by one day. There is no international date line which has been formally adopted by the various nations of the world. In 1884, the International Meridian Conference, held in Washington, D. C. , established the meridian of Greenwich as the meridian from which time was to be reckoned. The meridian 180^o from the Greenwich meridian thus became the international date line. The international date line in use by the U. S. Hydrographic Office is defined as follows: it is drawn from the North Pole due south along the 180th meridian to 75^o N. ; thence southeastward, to the east of Herald Island, to 68^o N and the longitude of the meridian passing between the Diomede Islands (approximately 168^o 58' 22" W. ); thence due south through the Bering Straits to 65^o 30' N. ; thence southwestward to 53^o N. , 170^o E. ; thence southeastward to 48^o N. and the 180th meridian; thence due south to 5^o S. ; thence southeastward to 15^o 00' S. , 172^o 30' W. ; thence due south to 45^o 00' S. , 172^o 30' W. ; thence southwestward to 51^o S. and the 180th meridian; thence south to the South Pole.