Galveston, Texas. Galveston (/ˈɡælvɪstən/ GAL-viss-tən) is a coastal resort city on Galveston Island and Pelican Island in the U.S. state of Texas. The community of 209.3 square miles (542 km2), with an estimated population of 50,180 in 2015, is the county seat and second-largest municipality of Galveston County.