Saint Kitts, also known more formally as Saint Christopher Island, is an island in the West Indies. The west side of the island borders the Caribbean Sea, and the eastern coast faces the Atlantic Ocean. Saint Kitts and the neighbouring island of Nevis constitute one country: the Federation of Saint Kitts and Nevis. Saint Kitts and Nevis are separated by a shallow 3-kilometre channel known as "The Narrows". Saint Kitts became home to the first Caribbean British and French colonies in the mid-1620s. Along with the island nation of Nevis, Saint Kitts was a member of the British West Indies until gaining independence on 19 September 1983. The island is one of the Leeward Islands in the Lesser Antilles. It is situated about 2,100 km (1,300 mi) southeast of Miami, Florida, US. The land area of Saint Kitts is about 168 km2 (65 sq mi), being approximately 29 km (18 mi) long and on average about 8 km (5.0 mi) across. Saint Kitts has a population of around 40,000, the majority of whom are of African descent. The primary language is English, with a literacy rate of approximately 98%. Residents call themselves Kittitians. Brimstone Hill Fortress National Park, a UNESCO World Heritage Site, is the largest fortress ever built in the Western Caribbean. The island of Saint Kitts is home to the Warner Park Cricket Stadium, which was used to host 2007 Cricket World Cup matches. This made Saint Kitts and Nevis the smallest nation to ever host a World Cup event. Saint Kitts is also home to several institutions of higher education, including Ross University School of Veterinary Medicine, Windsor University School of Medicine, and the University of Medicine and Health Sciences.