During the last 100 feet prior to an unmarked intersection a vehicle should slow to how many mile per hour?

During the last 100 feet prior to an unmarked intersection, a vehicle should generally slow down to around 15 to 20 miles per hour. This reduced speed allows the driver to safely assess the intersection, check for oncoming traffic, and make any necessary maneuvers. However, specific speed limits may vary by state or local regulations, so drivers should always be attentive to surrounding conditions.