Although tourist maps are useful resources for people to visit scenic areas, they are also commonly distorted and omit details according to the purposes and functions of a map. In this paper, we present iTour, a semi-automatic system that turns tourist maps into digital maps. By involving users in matching the road network of a tourist map and the paired standard map, our system computes road network correspondence between the two maps. By doing so, users can navigate on such GPS-enabled tourist maps using mobile devices. This transformation creates the possibility of augmenting a large number of tourist maps with digital map features. To evaluate the performance of matching road networks, we compared the presented semi-automatic interface to a manual interface. The results showed that the semi-automatic interface saved participants significant effort in generating correspondence and was perceived to require significantly less time by the participants. In addition, we conducted a field study of the iTour in comparison to using a tourist map and Google Maps together. Our results showed that iTour helped participants find their way during travel. The participants provided positive feedback on the combination of tourist maps and GPS location because of its highlights of important landmarks, showing users' locations relative to those landmarks, and saving the effort of switching tourist maps and Google Maps.