The island is about 27 miles (43 kilometers) long and no more than 3 miles (5 kilometers) wide at its widest point. The island is oriented generally northeast-southwest, with the Gulf of Mexico on the east and south, West Bay on the west, and Galveston Bay on the north. The island's main access point from the mainland is the Interstate Highway 45 causeway that crosses West Bay on the northeast side of the island. The far north end of the island is separated from the Bolivar Peninsula by Galveston Harbor, the entrance to Galveston Bay and the Houston Ship Channel. Ferry service is available between Galveston Island and the Bolivar Peninsula. The southern end of the island is separated from the mainland by San Luis Pass. The San Luis Pass-Vacek Toll Bridge connects the San Luis Pass Road on Galveston Island with the Bluewater Highway that leads south into the town of Surfside Beach.
Jao de la Porta, along with his brother Morin, financed the first settlement by Europeans on Galveston Island in 1816. Joa de la Porta was born in Portugal of Jewish parentage and later became a Jewish Texan trader. In 1818, Jean Laffite appointed Jao supercargo for the Karankawa Indian trade. When Laffite left Galveston Island in 1820, Jao became a full-time trader.
On September 8, 1900, the greatest natural disaster to ever strike the United States occurred at Galveston, Texas. In the early evening hours of September 8, the Galveston hurricane of 1900 came ashore, bringing with it a great storm surge that inundated most of Galveston Island and the city of Galveston. As a result, much of the city was destroyed and at least 6,000 people were killed in a few hours time.
Dr. Isaac M. Cline, the meteorologist in charge of the local Weather Bureau, lived on Galveston Island, just off the Texas coast. Cline was aware of a storm out in the Gulf based on previous reports from Florida. Although weather conditions were relatively calm on September 7, Dr. Cline observed the rough seas and the high waves that seemed to become more ominous by the hour. He sent a telegram to Washington, DC saying he thought a large part of the city was going to be underwater. He predicted a very heavy loss of life.