Big Isaac is an unincorporated community in Doddridge County, West Virginia, United States. Big Isaac is 6 miles south-southeast of Salem, along Laurel Run, a headwaters tributary of Meathouse Fork. …Big Isaac is an unincorporated community in Doddridge County, West Virginia, United States. Big Isaac is 6 miles south-southeast of Salem, along Laurel Run, a headwaters tributary of Meathouse Fork. The Big Isaac post office closed on December 31, 1962.