Florida has the most extensive barrier islands in the U.S., with many along its Atlantic and Gulf coasts.

Florida is home to the largest number of barrier islands in the United States, especially along its Atlantic and Gulf coasts. These islands, which include famous ones like the Florida Keys, serve as natural barriers that protect the mainland from storms and coastal erosion. While Texas, Louisiana, and South Carolina also have barrier islands, Florida's coastline is particularly extensive in terms of these islands, making it the state with the most.