 Known today as AK Steel, the industry remains a major employer in northeastern Kentucky.Ashland Oil, Inc., at one time the largest corporation headquartered in Kentucky, was started in 1924 at Leach Station, south of Catlettsburg, by Paul G. Blazer.Best known for their Valvoline Oil products, Ashland Oil relocated to Covington, Kentucky in 1999, merged with Marathon Oil, and sold its remaining petroleum shares to Marathon in 2005, dissolving their petroleum division.