Jupiter Island is a town in Martin County, Florida, United States. The population was 620 at the 2000 census. As of 2004, the population recorded by the U.S. Census Bureau is 653. Located north of another wealthy town, Palm Beach, Jupiter Island's closed community houses some of the wealthiest people in the United States, ranking 2nd on the list of the highest-income places in the country. Mail delivery is from the Hobe Sound post office and many town residents when away from the area will say they are from Hobe Sound. Jupiter Island apartments for rent comparison page shows most up to date rent information on Jupiter Island apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.