Provided are a computer program product, system, and method for distributing content to render at vehicles. A content instance indicates content and a content time period and a content location at which the content is to be rendered during the content time period. For each group of content instances having a same location and a content time period comprising beginning at a current time, a determination is made of vehicles having a vehicle location within the content location. For each group of content instances, a determination is made of an assignment of the content instances to a vehicle of the determined vehicles. For each vehicle assigned the content instances, a content package is transmitted having content from the assigned content instances to cause the assigned vehicle to display the content on a display screen coupled to the vehicle to be viewed by people in a vicinity of the vehicle.