With the 1923 sale of the Bayles Shipyard to the Standard Oil Company and demolition of all but two of its structures, Port Jefferson's shipbuilding industry came to a close. This resulted in an economic downturn and the closing of many of the grand hotels in Hotel Square as tourism declined along with the industry. Port Jefferson Harbor was repurposed for the oil transportation and gravel industries and, since the 1940s, as the site of a Long Island Lighting Company (LILCO) coal-fired power plant. The harbor also had activity as a rum-running center during the Prohibition era. It would not be until well into the 20th century that Port Jefferson rehabilitated its economy with tourism as its primary focus.