Digital travel sales is a $450 billion market worldwide (2014 figures by eMarketer). By 2017, 30% of travel sales in the United States will be generated through a mobile device (Statista). By 2018, mobile travel researchers will account for 71.3% of digital travel researchers in the US (eMarketer). Today already, 47% of travelers start planning a trip on a smartphone. Travel apps are, increasingly, where the purchase intent starts.To explore the huge travel opportunity on mobile, we teamed up with app store analytics company Priori Data and brought you an overview of the travel app category.