After the war, Mahone led the rebuilding of the N&P, and soon became involved in the South Side Railroad, which ran from Petersburg to Lynchburg, becoming its president as well. Reviving his prewar dream, he became the driving force in the linkage of N&P, South Side Railroad and the Virginia and Tennessee Railroad to form the Atlantic, Mississippi & Ohio Railroad (AM&O), a new line extending from Norfolk to Bristol, Virginia which was formed in 1870 after several years of lobbying of the Virginia General Assembly by Mahone and his political allies. William and Otelia Mahone moved to Lynchburg, where headquarters were established. The letters AM&O were said to stand for "All Mine and Otelia's."