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Child Passenger Safety (CPS)

Car Seat Purchasing and Installing

Not having the car seat installed properly in the vehicle decreases the effectiveness of the car seat to protect your child during a crash and increases the risk of injury and death. A properly installed car seat does not move more than 1" from front to back and from side to side where it is attached to the vehicle, with the exception of booster seats, which are not installed in the vehicle. The main misuse error made when installing a car seat is that the car seat is too loose.

There are two ways to install a car seat:

  • with the vehicle's seat belt
  • with LATCH (Lower Anchors and Tethers for CHildren)

A car seat can be installed using either the vehicle's lap-only seat belt or lap and shoulder seat belt. Each car seat has a specific location where the seat belt must be threaded to secure the car seat. This is often referred to as a "belt path".

Each car seat has at least one belt path (though a convertible seat has two belt paths;) one for a rear-facing installation and the other for a forward-facing installation. Refer to the car seat instruction manual to find the correct belt path for your car seat.

Seat Belt Installation

  • Once the seat belt is threaded through the correct belt path and buckled, it must be tightened and locked. The seat belt will either lock at the latchplate or at the retractor. For vehicles 1995 and older, you may need to use a locking clip to install the car seat. Your vehicle owner's manual will instruct you on how to lock your seat belt when installing a child safety seat.
  • Ensure that the seat does not more than 1" from side to side or front to back when tugged at the belt path.
  • When installing your forward-facing car seat with a seat belt, you should also attached the car seat's top tether strap to the tether anchor in the vehicle. The tether will reduce the amount of forward movement your child's head will travel during a crash. It improves the safety of the car seat and reduces the risk of head, brain and spinal injury to your child. Most model year 2000 vehicles have a factory installed tether anchor to attach the tether strap to. The vehicle owner's manual will identify the proper location of the tether anchor.

LATCH Installation

If your vehicle is equipment with LATCH (Lower Anchors and Tethers for CHildren), you may be able to install the car seat without using the vehicle seat belt. LATCH consists of two lower anchors in the seat crack of the vehicle that attach to two lower attachment straps on the car seat and a top tether anchor in the vehicle that attach to the top tether strap on the car seat. LATCH was developed to make car seat installation easier by eliminating the need to learn how to lock a seat belt and to eliminate seat belt incompatibility issues. Vehicles with a model year of 2003 or newer are equipment with LATCH.

  • There are metal anchors in the seat crack that the LATCH straps on the car seat attach to.
  • Once attached, the straps must be tightened so that the car seat doesn't move more than 1" from side to side or from front to back.

LATCH often has a weight limit of 40 or 48 pounds so consult with the vehicle owner's manual and the car seat instruction manual to determine the weight limit of LATCH.

LATCH is not a safer installation than a seat belt installation and may not always be easier to use. Choose whichever installation method provides for the best and easiest fit for you. Never use both the seat belt AND the lower attachments portion of the LATCH system. It is best practice, and sometimes required by the car seat manufacturer, to always use a top tether on forward-facing car seats whether you are using the seat belt or the lower attachments to install the car seat.

Since booster seats elevate the child so that the lap and shoulder seat belt fit the child properly, they are not installed but rather serve as a pre-crash positioning device. However, when they are not in use, they should still be secured by the seat belt to prevent the unoccupied booster seat from becoming a flying projectile in a crash. Some manufacturers are designing booster seats that can be installed with LATCH to provide better pre-crash positioning and to secure an unoccupied booster seat. Refer to the booster seat instruction manual for correct use of the seat.

With over 90% of car seats misused, it is highly recommended to have your seat inspected by a Certified Child Passenger Safety Technician to learn the proper way to install and use your car seat. View the calendar of events to find a car seat inspection event near you.

Car Seat Harness

Of all of the errors that are made with car seats, half of them are how the child is buckled into the car seat.

  • For rear-facing children, the harness straps need to be at or below the child's shoulders.
  • For forward-facing children, the harness straps need to be at or above the child's shoulders.
  • Car seat manufacturers have various instructions about their particular products so always consult with the car seat instruction manual to determine which harness slot is appropriate for your child.

Car Seat Harness Tips

  • The harness must be snug on the child in order for it to perform best during a crash. A snug harness should not allow any slack. It lies in a relatively straight line without sagging. It does not press on the child’s ?esh or push the child’s body into an un-natural position. The recommended method to use to test for harness snugness is the "pinch test". You should not be able to pinch excess webbing at the shoulder once the harness is buckled.
  • The harness retainer clip, which is the plastic clip that snaps together on the child's chest, must be positioned at armpit level. The purpose of the clip is to hold the harness straps onto the child's shoulders during a crash. If the clip is too low, the harness could slip off the child's shoulders and the child would not be properly protected.
  • Harness straps should not be twisted, frayed or otherwise damaged. If the straps are damaged, contact the car seat manufacturer to receive replacement straps. Follow the instructions in the car seat instruction manual on how to properly clean the harness straps and the car seat padding to ensure that they are cleaned correctly.
  • Do not place any blankets or thick, bulky clothing behind or under the child or under the harness straps. Any excess bulk can compress during a crash leaving the harness loose on the child. It is best to cover the child with a blanket after the child is buckled into the car seat to provide warmth for the child.
  • Do not add any item to the car seat or to the harness straps that did not come with the car seat or is not approved for use by the car seat manufacturer. Adding non-regulated products may cause the seat to not function properly during a crash and may place your child at a higher risk of injury.

With booster seats, always use them with a lap and shoulder seat belt (never with a lap-only seat belt). Ensure that the seat belt is not twisted and is snug on the child, with the shoulder belt resting across the child's chest and collarbone and not behind their back or under their arm.

Consult with a Certified Child Passenger Safety Technician for education and an inspection of your child's car seat.


Do you need your child's car seat checked for correct installation in the vehicle and/or to know if it's the proper seat for your child? View a list of Maine Inspection Locations.