What can be considered the first major exploration of the Sacramento River, from its mouth northward, began on May 13, 1817, when Padres Duran and Abella and 20 other men under the command of Lt. Louis Antonio Argullo sailed in two launches up the river. They continued north until May 20, 1817, when they turned back. The group recorded their point of farthest exploration by carving a cross into an oak tree; some believe this point is near the present-day town of Freeport. Three decades later, Clarksburg was established, followed by Walnut Grove, Paintersville, Rio Vista, Onsibo, Freeport, Courtland, Emmaton, Isleton, Vorden, Ryde, Hood, and Locke. Each one of the settlements has its own exciting tale about its founders and the origins of the name that it was given.