South Bay is a city in Palm Beach County, Florida, United States. It is the westernmost municipality in the South Florida metropolitan area. The population was 3,859 at the 2000 census. As of 2007, the population recorded by the U.S. Census Bureau was 4,506. While the current estimates place South Bay's population in the incorporated city limits at more than 4,000 people, surrounding areas increase the population figures to 54,000 people in a 25-mile (40 km) radius and more than 1.4 million in a 50-mile (80 km) radius.