Somerdale is an unincorporated community in northeastern Fairfield Township, Tuscarawas County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 44678. It lies along State Route 212, Conotton Creek and the Wheeling and Lake Erie Railway east of Zoar.A post office called Somerdale has been in operation since 1887. Somerdale was originally a mining community and the Somerdale Coal Company operated there. Peak coal production at Somerdale was around the year 1900.