OpenStreetMap has grown rapidly into an exemplary geowiki, where contributors collectively build an open map of the world. Official ‘mapping party’ events are organized on a regular basis to invite users to socialize, map and to engage new-comers locally. Here, we measure the direct and indirect impact of mapping parties on user contributions in both the short and long terms. We question whether this social mapping is a cause for users to become highly committed through a social bond, or is an effect of the mappers’ need to find a common social ground. We show that mapping parties have distinct effects on different types of users, with a more profound direct impact on weaker contributors and a longer term effect on heavy contributors.