Following Distance and Stopping

Key points

1. Leave at least 1 car length for every 10 mph of speed.

   Source: Handbook p. 32

   “allow at least one car length between you for every ten miles per hour of speed.”
   Mississippi Driver's Manual, Handbook p. 32

2. At 40 mph leave at least 4 car lengths.

   Source: Handbook p. 32

   “@ 40 MPH leave at least FOUR (4) car lengths”
   Mississippi Driver's Manual, Handbook p. 32

3. Leave even more room behind a large truck or bus.

   Source: Handbook p. 32

   “When you are following a large truck or bus, allow yourself even more room.”
   Mississippi Driver's Manual, Handbook p. 32

4. At 20 mph it takes 68 feet to stop.

   Source: Handbook p. 33

   “@ 20 MPH - 68 feet to stop”
   Mississippi Driver's Manual, Handbook p. 33

5. At 50 mph, total stopping distance is 245 feet.

   Source: Handbook p. 33

   “@ 50 MPH - 245 feet to stop”
   Mississippi Driver's Manual, Handbook p. 33

6. At 70 mph, total stopping distance is 415 feet.

   Source: Handbook p. 33

   “@ 70 MPH - 415 feet to stop”
   Mississippi Driver's Manual, Handbook p. 33

7. Bad weather, slick roads, fatigue or alcohol make stopping distances drastically different.

   Source: Handbook p. 33

   “If the weather is bad, the road is slick, or if you are tired or intoxicated, then the distances will be drastically different”
   Mississippi Driver's Manual, Handbook p. 33

8. On the interstate, stay at least 7 car lengths back at 70 mph.

   Source: Handbook p. 57

   “If you are driving at seventy (70) mph, stay at least seven car lengths from the vehicle ahead.”
   Mississippi Driver's Manual, Handbook p. 57

Numbers to know

3 questions from the Mississippi practice test

1. 1. What following-distance guideline does the Mississippi manual give for a vehicle traveling 40 miles per hour?

   1. At least two car lengths
   2. At least three car lengths
   3. At least six car lengths
   4. At least four car lengths
   Show answer

   At least four car lengths. The following guideline assigns at least one car length for every ten miles per hour. At forty miles per hour, that produces at least four car lengths. Two or three lengths leave less room than the stated relationship, while six is not the figure shown for that speed. The purpose is to create time and space when the vehicle ahead changes speed suddenly and to improve the view around it. Increase the gap further behind a large truck or bus, where visibility is reduced.

2. 2. At 50 mph, what following space does the manual recommend as a basic guide?

   1. A distance of one-half a car length in heavy traffic
   2. One car length, regardless of speed
   3. Two car lengths only when the road is wet
   4. At least five car lengths behind the vehicle ahead
   Show answer

   At least five car lengths behind the vehicle ahead. The manual ties a basic following interval to speed: allow at least one car length for every ten miles per hour. At 50 mph, that produces five car lengths, giving time and room to react if the vehicle ahead changes speed suddenly. One fixed car length ignores speed, and the wet-road option understates the space needed in a normal condition. Use the estimate as a starting point, then increase it for poor weather, a large vehicle, or limited visibility.

3. 3. How can bad weather, a slick road, tiredness, or intoxication affect stopping distance?

   1. The distance is unchanged if the driver uses high beams
   2. The distance becomes exactly half the chart value
   3. The distance can be drastically different from the ideal-condition chart
   4. The distance disappears once the driver pumps the brakes
   Show answer

   The distance can be drastically different from the ideal-condition chart. The manual warns that bad weather, a slick road, tiredness, or intoxication can make stopping distances drastically different from the chart. The half-distance claim invents a number, while high beams address seeing rather than tire grip or reaction ability. Pumping the brakes cannot erase the space needed to perceive a hazard and stop. Use the chart only as an ideal baseline, then create extra room when any listed condition reduces traction, alertness, or predictable braking performance.

Source: the Mississippi Driver's Manual, Rules of the Road: Following and Braking. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.