When to upsize the booster seat & Child Restraint Regulations

I have been reading a fair amount of questions from parents asking when is the time to change from the harness seat to a booster seat. To answer those questions, I have put together the following information, based on information from the National Highway Traffic Safety Administration.

As your child grows up, there are 4 Steps, according to their age and size:

1 - REAR FACING SEATS in the back seat from birth to at least 1 year old and at least 20 pounds.

2 - FORWARD-FACING TODDLER SEATS in the back seat from age 1 and 20 pounds to about age 4 and 40 pounds.

3 - BOOSTER SEATS in the back seat from about age 4 to at least age 8, unless 4'9" tall.

4 - SAFETY BELTS at age 8 and older or taller than 4'9". All children age 12 and under should ride in the back seat.

Restraint requirements change for each State. Here is an extract from DMV Answers:

Child Restraint Requirements
Alabama
Younger than 1 or less than 20 pounds in a rear-facing infant seat; 1-4 years or 20-40 pounds in a forward-facing child safety seat; 5-6 years in a booster
Alaska
Younger than 1 or less than 20 pounds in a rear-facing infant seat; 1-4 years and more than 20 pounds in a child restraint, 4-8 and shorter than 57 inches or 20-65 pounds in a booster
Arizona
Under 5
Arkansas
Under 6 and less than 60 pounds
California
Under 5 and less than 60 pounds
Colorado
Younger than 1 year and less than 20 pounds in a rear-facing infant seat; 1-3 years and 20-40 pounds in a forward-facing child safety seat; 4-5 years and less than 55 inches in a booster
Connecticut
Younger than 1 year or less than 20 pounds in a rear-facing restraint system; 1-6 years and less than 60 pounds in a child restraint system
Delaware
Under 7 and less than 66 pounds
Florida
Children under 3 should be in a separate car seat or a car seat that is integrated into the vehicle; children 4- 5 can use a separate car seat, integrated car seat, or seat belt
Georgia
Under 5 and less than 57 inches
Hawaii
Under 3 in a child safety seat; children 4-7 must be in a booster or child restraint
Idaho
Under 6
Illinois
Under 7
Indiana
Under 7
Iowa
Younger than 1 year and less than 20 pounds in a rear-facing child seat; children 1-5 in a child restraint
Kansas
All children 3 and younger must be in a child restraint; children 4-7 who weigh less than 80 pounds and are less than 57 inches tall must be in a child restraint or booster
Kentucky
40 inches or less in a child restraint; under 6 and 40-50 inches tall in a booster
Louisiana
Younger than 1 year or less than 20 pounds in a child safety seat; 1-3 years or 20-39 pounds in a forward-facing child safety seat; children 4-5 or 40-60 pounds in a booster
Maine
Less than 40 pounds in a child safety seat; 40-80 pounds and less than 8 years in a booster
Maryland
Under 7 and less than 57 inches or 65 pounds
Massachusetts
Under 7 and less than 57 inches
Michigan
Under 7 and less than 57 inches
Minnesota
Under 7 and less than 57 inches
Mississippi
3 years and younger must be in a child restraint; children 4-6 and either less than 57 inches or less than 65 pounds must be in a booster
Missouri
Under 3 or less than 40 pounds must be in a child restraint; children 4-7 years who weigh at least 40-80 pounds and are under 57 inches must be in either a child restraint or booster
Montana
Under 6 and less than 60 pounds
Nebraska
Under 5
Nevada
Under 6 and less than 60 pounds
New Hampshire
Under 5 and less than 55 inches
New Jersey
Under 7 and less than 80 pounds
New Mexico
Younger than 1 year in a rear-facing infant seat; children 1-4 or less than 40 pounds in a child safety seat; children 5-6 or less than 60 pounds in a booster
New York
Children under 8 should be in either a child safety seat or booster seat
North Carolina
Under 7 and less than 80 pounds
North Dakota
Under 7, less than 57 inches, or less than 80 pounds
Ohio
Under 3 or less than 40 pounds in child restraint; 4-7 years, over 40 pounds, and less than 57 inches in booster
Oklahoma
Under 5
Oregon
Younger than 1 year or 20 pounds or less must be in a rear facing child safety seat; 40 pounds or less must be in a child safety seat; more than 40 pounds but 4 feet and 9 inches or less must be in a safety system that elevates the child so that an adult seat belt fits properly
Pennsylvania
Under 7
Rhode Island
Under 7, less than 57 inches, and less than 80 pounds
South Carolina
Younger than 1 year or less than 20 pounds in a rear-facing infant seat; 1-5 years and 20-39 pounds in a forward-facing child safety seat; 1-5 years and 40-80 pounds in a booster secured by lap-shoulder belt
South Dakota
under 4 and under 40 pounds
Tennessee
Younger than 1 year or under 20 pounds in a rear-facing infant seat; 1-3 years and over 20 pounds in a forward-facing infant seat; 4-8 years and less than 57 inches in a booster
Texas
Under 7 and less than 57 inches
Utah
Under 7 and less than 57 inches
Vermont
Younger than 1 year or less than 20 pounds in a rear-facing infant seat; children 2-7 and more than 20 pounds in child restraint
Virginia Under 7, unless there is a physician exemption
Washington
Under 7 and less than 57 inches
West Virginia
Under 7 and less than 57 inches
Wisconsin
Children younger than 1 and all children who weigh less than 20 pounds are required to be in a rear-facing infant seat; children 1-3 years who weigh at 20-40 pounds are required to be in a forward-facing child safety seat; children 4-7, less than 80 pounds, and less than 57 inches tall are required to be in a booster
Wyoming
Under 8
Washington DC
Under 7

I am glad if this clarifies some of your questions about when to switch to a child's booster seat.