For example, at UTC Thursday, it is Wednesday in American Samoa (UTC−), Thursday in most of the world, and Friday in Kiritimati (UTC ).During the first hour (UTC –), all three calendar dates include inhabited places.American Samoa, the Cook Islands, Niue, and French Polynesia are east of the IDL and one day behind. It follows that meridian until reaching Antarctica, which has multiple time zones.Conventionally, the IDL is not drawn into Antarctica on most maps.Night and day is illustrative only; daylight hours depend on latitude and time of year.) 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 the 180° meridian exactly.The areas that are the first to see the daylight of a new day vary by the season.Around the June solstice, the first area would be anyplace within the Kamchatka Time Zone (UTC ) that is far enough north to experience midnight sun on the given date.
This date line can be called de facto since it is not based on international law, but on national laws.
At the equinoxes, the first place to see daylight would be the uninhabited Millennium Island in Kiribati, which is the easternmost land located west of the IDL.
Near the December solstice, the first places would be Antarctic research stations using New Zealand Time (UTC ) during summer that experience midnight sun.
In other places, however, the IDL deviates east or west away from that meridian. Aleutian Islands (Attu Island being the westernmost) and the Commander Islands, which belong to Russia. Thus, all of Russia is to the west of the IDL, and all of the United States is to the east except for the insular areas of Guam, the Northern Mariana Islands, and Wake Island.
These various deviations generally accommodate the political and/or economic affiliations of the affected areas. The IDL remains on the 180° meridian until passing the equator.