Apparatuses, methods, and computer programs for displaying information on signs

A system shows messages on electronic displays, including networks of outdoor displays, such as displays mounted on vehicles. With such vehicle displays, a display's current geographical location can be sensed, such as by a GPS receiver in the vehicle or by multiple wireless receivers separate from the vehicle. The sensed location can then be used to select which messages are shown the display. Different values can be associated with showing messages on displays at different locations and times, and values associated with the locations and time through which a display travels can be summed, such as for charging advertisers or crediting vehicle operators. The system can be controlled by a computer system, such as an e-commerce site, which allows advertisers to upload message content, select messages, and select the time and place at which a messages is to be shown, either directly or by specifying criteria for the system to select such times and places. Message content and information controlling which messages are shown when and where can be downloaded to display, such as by wireless.