Locating passenger transit vehicles by detecting interactions. Each interaction is between a transit terminal and a geolocation-enabled user device, and is characterized by data indicative of the interacting terminal, the interacting user device, and the time of interaction. For each detected interaction, a geolocation of the corresponding user device at the time of the interaction is requested; and in response to the requesting, the geolocation of the corresponding user device, the time of the geolocation, and the data indicative of the interacting terminal is received. A particular passenger transit vehicle associated with at least one interacting terminal is identified based on the user device geolocations. The location of the passenger transit vehicle is transmitted for display on user devices.