The rail line now called Caltrain was started in the 1860s to create a faster alternative to stagecoaches and ships between the key cities of San Francisco and San Jose. Operated by Southern Pacific for many years, the Peninsula Commute Service is the oldest continuously operating passenger railroad in the West and boasts seven depots in the National Register of Historic Places. This indomitable iron horse has filled a vital transportation role, from evacuating San Franciscans during the 1906 earthquake to getting commuters to work. With the dawn of the 21st century, Caltrain reinvented itself yet again with its innovative Baby Bullet express trains. Coauthor of two Arcadia Publishing titles on Redwood City, Janet McGovern formerly worked in Caltrain's marketing department and covered the Peninsula Commute Service as a reporter. Tapping the collections of Caltrain, the Union Pacific Museum, and the California State Railroad Museum as well as private collections, McGovern shows not only how this rail line has evolved but also how it has helped the San Francisco Peninsula transform from ranchos to towns to suburbs to today's Silicon Valley.