The world's largest operating steam locomotive, Big Boy No. 4014, has arrived in Philadelphia for a coast-to-coast tour of the last of the steam engines that opened the West in commemoration of America's 250th anniversary. The tour will include major stops in Scranton and Altoona, including those in Philadelphia. The Union Pacific Museum will be selling tickets to ride in vintage passenger cars pulled by Big Boy through the Poconos Mountains on June 14. The eastern leg of the tour includes major events and over 50 whistle stops in 10 states. The route through the Ohio Valley, Pennsylvania and the Northeast reflects the historic role railroads have played in shaping America's economic growth.