Shown on a topographic map are floodmark elevations and approximate areas flooded by Hurricane Frederic tides of September 12-13, 1979, along coastal areas of Mississippi Sound from about one mile east of the Alabama-Mississippi State line westward to the Jackson County Airport in Mississippi. Storm-tide frequency and records of annual maximum tides at Mobile, Alabama, since 1772, are presented. Tide elevations in this region were about equal to those produced by Hurricane Betsy in September 1965. Offshore winds reached about 160 miles per hour. A wind-velocity of about 145 miles per hour was recorded near Dauphin Island, Alabama, a few miles southeast of Grand Bay. (USGS)