Byrnesville was a town located in Conyngham Township, Columbia County, Pennsylvania, United States. It was located about halfway between Centralia and Ashland. In 1985, the population of Byrnesville was approximately 75. Byrnesville was founded in 1856. Most of the residents were Irish Catholics who worked in the local anthracite coal mines. It was made up of Upper and Lower Byrnesville. The first homes were built in Lower Byrnesville around 1856 and in Upper Byrnesville around 1865. An elementary school was located in Byrnesville but was discontinued in the 1930s.