In 1698 the French explorer Pierre Le Moyne, Sieur d'Iberville, sailed into the mouth of this river and found pearls, naming it the "River of Pearls." A hundred years later, the Natchez Trace avoided the marshy lowlands by following the ridge between the Pearl and the Big Black for 150 miles. Since 1812, the last 75 miles of the river's course have served as a boundary between Mississippi and Louisiana.