Hejaz Railway
During World War I, the German Army produced shale oil from the Jordan oil shale at the Yarmouk area to operate the Hejaz Railway. In 1915 an oil shale industry was established in Switzerland. About 1920, a small mall shale oil extraction plant was opened at Kinnekulle, Sweden. In 1922, a small shale oil extraction plant was opened in Puertollano, Spain.