McMellen's wife’s name was Annie E. Wenditz (Nov. 13, 1841-April 1, 1899). They were married on 21 Sep 1865 and had the following children: Ella, Sara (also known as Sadie), Joseph, Walter and James. Their home for many years was located at 28 East Vine Street,Lancaster, Pennsylvania; he provided a home for his mother next-door.
During the Civil War, McMellen enlisted for service in the Union Army, becoming a private in Co. K, 79th P. V. I., which regiment was assigned to Gen. Negley's brigade. At Perryville, he contracted camp fever through exposure, and was sent home on a furlough. In 1863 he was mustered out of the 79th Regiment on a surgeon's certificate, and the same year, when his health had somewhat recovered, was again received into the service, as first lieutenant of Co. C, 21st Pa. Cavalry. Later, he was appointed captain of the Color Company of the regiment, Co. 1, 21st Pa. Cavalry. Capt. McMellen participated in the last charge made by the Army of the Potomac, on the morning of the surrender of Gen. Robert E. Lee.
When he was twenty years old he built the bridge over Chickies Creek, at Snavely's Mill, and went on to build some of the most celebrated covered bridges in Pennsylvania. In this work of building and contracting he was very successful, and many iron, wooden and stone bridges in Lancaster and adjoining counties were erected by him, his reputation as a bridge builder being second to that of no man in eastern Pennsylvania. He died some time after 1902.
McMellen's Bridges include: