Historical population figures for the Marshall Islands are unknown. In 1862, the population of the Islands was estimated at 10,000. In 1960, the population of the Islands was approximately 15,000. The 2011 Census counted 53,158 island residents. Over two-thirds of the residents of the Marshall Islands live in the capital city, Majuro, and the secondary urban center, Ebeye (located in Kwajalein Atoll). This figures excludes Marshall Islands natives who have relocated elsewhere; the Compact of Free Association allows them to freely relocate to the United States and obtain work there. Approximately 4,300 Marshall Islands natives relocated to Springdale, Arkansas in the United States; this figure represents the largest population concentration of Marshall Islands natives outside their island home.