Seat belts, child seats and following distance

Key points

1. The driver and front seat occupants must wear seat belts, and all passengers of an intermediate license holder must be restrained.

   Source: Handbook p. 55

   “Missouri law requires the operator and front seat occupants of all passenger vehicles to wear a properly adjusted and fastened seat belt. However, ALL passengers accompanying an intermediate driver license holder must be properly restrained.”
   Missouri Driver Guide, Handbook p. 55

2. Children under 4, regardless of weight, must ride in a child passenger restraint system.

   Source: Handbook p. 55

   “Children less than four years old, regardless of weight, shall be secured in a child passenger restraint system appropriate for that child.”
   Missouri Driver Guide, Handbook p. 55

3. Children 4 to under 8 who weigh 40 to under 80 pounds and are under 4 feet 9 inches need a child seat or booster.

   Source: Handbook p. 56

   “Children at least four years of age but less than eight years of age, who also weigh at least 40 pounds but less than 80 pounds, and are also less than 4’9” tall shall be secured in a child passenger restraint system or booster seat”
   Missouri Driver Guide, Handbook p. 56

4. Children 12 and under should ride properly restrained in a rear seat.

   Source: Handbook p. 55

   “Children 12 and under should always ride properly restrained in a rear seat.”
   Missouri Driver Guide, Handbook p. 55

5. Sit with at least 10 inches between your breastbone and the steering wheel.

   Source: Handbook p. 55

   “recommends drivers sit with at least ten inches between the center of their breastbone and the center of the steering wheel.”
   Missouri Driver Guide, Handbook p. 55

6. Use the three second rule to measure a safe following distance.

   Source: Handbook p. 57

   “A good way to measure your safe following distance is to use the “three second rule.””
   Missouri Driver Guide, Handbook p. 57

7. If a tailgater follows you and there is a right lane, move over to the right.

   Source: Handbook p. 57

   “you are followed too closely or “tailgated” by another driver, and there is a right lane, move over to the right.”
   Missouri Driver Guide, Handbook p. 57

8. Stopping distance is reaction distance plus braking distance.

   Source: Handbook p. 58

   “Your stopping distance equals your reaction distance plus your braking distance.”
   Missouri Driver Guide, Handbook p. 58

9. Signal as early as you can, at least 100 feet before you make your move.

   Source: Handbook p. 58

   “Signal as early as you can. Try to signal at least 100 feet before you make your move.”
   Missouri Driver Guide, Handbook p. 58

10. Deer seldom travel alone, so expect more nearby when you see one.

    Source: Handbook p. 59

    “Deer seldom travel alone. Chances are if you see one deer crossing a road or notice a struck deer on the side of the road, there are others nearby.”
    Missouri Driver Guide, Handbook p. 59

Numbers to know

3 questions from the Missouri practice test

1. 1. Under Missouri's child passenger restraint classifications, which child must use a child passenger restraint system regardless of weight?

   1. A child at least eight years old and at least 80 pounds
   2. A child taller than 4 feet 9 inches
   3. A child less than four years old
   4. A child exactly four years old who weighs 80 pounds
   Show answer

   A child less than four years old. Missouri's classification makes age alone decisive for a child younger than four. That child must be secured in a child passenger restraint system regardless of weight. The option using age eight and weight 80 pounds describes the older-child category, where a vehicle safety belt or suitable booster seat is allowed. Height above 4 feet 9 inches also belongs to that older category. A child exactly four years old is outside the less-than-four rule, so the wording matters. Before driving, match the child to every applicable age, weight, and height threshold rather than relying on one number in isolation.

2. 2. How can a Missouri driver measure a safe following distance in ordinary conditions?

   1. Stay one car length behind at every speed
   2. Use the three second rule with a roadside object
   3. Follow close enough to read the lead vehicle's plate
   4. Use a one second gap when traffic is moving
   Show answer

   Use the three second rule with a roadside object. The three second rule gives a practical way to judge space behind another vehicle. Pick a fixed object near the road, begin counting as the vehicle ahead passes it, and make sure your vehicle does not reach that object before the count ends. A single car length changes meaning with speed, while following close enough to read a plate removes useful reaction room. Increase the gap when weather, visibility, traffic, or vehicle condition makes stopping more difficult.

3. 3. If another driver is following your vehicle too closely and a right lane is available, you should:

   1. Move over to the right
   2. Speed up until the other vehicle stops following
   3. Block the right lane so the driver cannot pass
   4. Brake suddenly to make the driver back off
   Show answer

   Move over to the right. When a tailgater is behind you and a right lane is available, move over to the right so the other driver can pass. This separates the vehicles without a sudden confrontation. Hard braking is dangerous because it removes the following driver's stopping margin, while speeding can encourage more aggressive driving. Check the right lane, signal, and move when safe. If no right lane exists, reduce speed gradually only after the road ahead is clear, never with an abrupt stop.

Source: the Missouri Driver Guide, Chapter 8: Safe Driving Tips For Everyday Driving. 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.