Hattiesburg is a city in the U.S. state of Mississippi, primarily in Forrest County and extending west into Lamar County. The city population was 45,989 at the 2010 census, with an estimated population of 46,805 in 2015. It is the principal city of the Hattiesburg, Mississippi, Metropolitan Statistical Area, which encompasses Forrest, Lamar and Perry counties.Development of the interior of Mississippi by European Americans took place primarily after the American Civil War. Before that time, only properties along the major rivers were developed as plantations. Founded in 1882 by civil engineer William H. Hardy, Hattiesburg was named in honor of Hardy's wife Hattie. The town was incorporated two years later with a population of 400. Hattiesburg's population first expanded as a center of the lumber and railroad industries, from which was derived the nickname "The Hub City".