Tourism is an international industry worth trillions of dollars, which creates hundreds of millions of jobs worldwide — but that wasn’t always the case. In his book, “A History of Modern Tourism,” University of New England history professor Eric Zuelow walks us through the story of how we learned to love travel. From diplomacy, to new technologies like steam power, to a growing need for adventure and self-expression, tourism has become a global phenomenon with a huge impact on the places we love to visit and the environment.