At roughly 15 miles long and 5 miles across at its widest, Sanibel Island is world-renowned for its sugar-white sandy beaches and abundance of seashells. Most of the city proper is at the east end of the island. After the Sanibel causeway was built to replace the ferry in May 1963, the city was incorporated eleven years later in 1974. There are twenty-five miles of bike paths for you to explore the island. More than half of the island is comprised of wildlife refuges, the largest being J.N. "Ding" Darling National Wildlife Refuge. The island does offer one public school. The Sanibel School is for kindergarten through 8th grade and is part of the Lee County School District.