Historical data based navigational routing

Navigational routing is generated incorporating an estimation of future traffic conditions. The future traffic conditions are estimated based on historical traffic data, e.g., obtained over a recent period of time. The system provides navigational routing based on historical traffic data incorporated into a calculated route of travel. The historical data is used to calculate a probability that given roads along the route will be problematic at a certain time of the day, i.e., at the time, day of week, and place that you would be expected to be traveling on that certain road. Accordingly, historical traffic data is used to help determine a best route based on the probability of certain roads being problematic at a certain time of day.