 Mercer Island is in the Seattle Metropolitan Area, with Seattle to its west and Bellevue to its east.Mercer Island is connected to the mainland on both sides by bridges carrying Interstate 90.The Lacey V. Murrow Memorial Bridge and the parallel Homer M. Hadley Memorial Bridge are floating bridges that span Lake Washington and carry, respectively, eastbound and westbound lanes of Interstate 90 and connect Mercer Island to the northern portion of Seattle's South End.