Galveston Bay is the second-busiest port in the nation by overall tonnage. Other major ports utilizing the bay include the Port of Texas City and the Port of Galveston. With its diverse marine life, Galveston Bay also produces more seafood than any bay in the nation except the Chesapeake. The Gulf Coast gained its present configuration during the most recent glacial period approximately 18 ka (thousands of years ago). Low global sea levels allowed the Texas mainland to extend significantly further south than it is presently, and the Trinity River had carved a deep canyon through present-day Bolivar Roads on its way
Galveston Island would hold until nearly the end of the 19th century. Galveston for a time before the American Civil War was the largest cotton shipping port in the world and the second-largest port for immigration in the United States. In the mid-19th century, it was a major port of entry for the many Germans who entered the state. During the Civil War, the Union army seized control of the island from the South for a few months during early 1863. Confederate forces commanded by John B. Magruder expelled them from the island, and the Confederates controlled it for the remainder of