Idaho State Statute (49-654) relates to speed.  Vehicles should not be driven at a speed greater than is reasonable and prudent under the conditions and having regard to the actual and potential hazards then existing.

• 75mph – on interstate highways

• 65mph – on state highways

• 55mph – other locations

• 35mph    - residential, business or urban districts

School Zones will have a posted speed limits and any infraction will have a minimum fine of $75 with additional court fees of $41.50.

Construction Zones are considered danger zones and violating the speed limit can result in an additional fine of $50.
It is also illegal to drive so slowly that you disrupt the normal flow of traffic. Regardless of what the posted speed limit is, you need to judge the situation and slow down to a speed that will allow you to operate your vehicle safely.