This tiny Alaskan island is America's most extreme north-westerly possession. The Diomede Islands are located in the middle of the Bering Strait between mainland Alaska and Siberia, with the Chukchi Sea to the north and the Bering Sea to the south. 9.3 km (5.8 mi) to the southeast is Fairway Rock, which is generally not considered part of the Diomede Islands. The islands are sometimes called Tomorrow Island (Big Diomede) and Yesterday Isle (Little Diomede) because they are separated by the International Date Line, thus Big Diomede is 23 hours ahead of Little Diomede. Little Diomede Island (native name Ignaluk; formerly known as Krusenstern Island, which can also refer to other places) is an island of Alaska, United States. It is the smaller of the two Diomede Islands located in the middle of the Bering Strait between the Alaska mainland and Siberia. Its neighboring island Big Diomede is less than 2.4 mi (3.9 km) to the west, but is part of Russia and west of the International Date Line. Little Diomede has an estimated population of 135. The entirety of the island is in the city of Diomede, also known by its native name Inalik. The island is not part of any organized borough, so some services are provided directly by the state. For census purposes, it is included in the Nome Census Area. During the winter, the town villagers carve a runway into the thick ice sheet so that bush planes can deliver vital products, such as medicine. Due to annual variations of the ice sheet, the runway changes position every year. There are also helicopter flights. The Little Diomede island is composed of Cretaceous age granite or quartz monzonite. The location of the city is the only area which does not have near-vertical cliffs to the water. Behind the city and around the entire island rocky slopes rise at about 40° up to the relatively flattened top in 1,148–1,191 feet (350–363 m). The island has very scant vegetation.