WASHINGTON — Ford Motor Co. is mounting a campaign to persuade lawmakers in every state to require booster seats for children who are too big for child safety seats but too small to use adult seat belts alone.

Three states — Washington, California and Arkansas — have passed laws requiring booster seats for children age 4-8, and about 20 other states are considering them.

"This is not different really than seat-belt legislation," Ford President Jac Nasser said. "Appropriate legislation in conjunction with education makes sense."

Booster seats can vary in appearance, but usually look like the seats children use to reach the table at a restaurant. They elevate the child so the seat belt fits properly across the shoulder and lap.

Size is more important than age in determining how long to use a booster seat. The federal government recommends that children from 40 to 80 pounds and less than 4 feet 9 inches tall should always use them.

All states require car seats for the smallest children, usually up to 4 years old, but federal data show that less than 10 percent of children between 4 and 8 use booster seats.

On Monday, Ford was embarking on a $30 million campaign that encourages parents to use the seats. It includes giving away 1 million booster seats.

Ford also was releasing a survey showing that while 88 percent of caregivers have heard of booster seats, only 21 percent use them. Seventy-one percent did not know the proper age at which a child should use a booster seat.

The survey involved 11,701 telephone interviews conducted by Wirthlin Worldwide of McLean, Va., from Dec. 18 to Jan. 28. It has an error margin of 1.1 percentage points.

A survey conducted in December by DaimlerChrysler AG's Fit for a Kid program found that 96 percent of caregivers did not know the correct age at which a child no longer requires a child safety seat or booster seat.

Ford has distributed educational kits to every public elementary school and accredited preschool in the country.

The materials distributed to the preschools feature characters from Nickelodeon's "Blue's Clues," while the elementary students get a message from actors Will and Jada Pinkett Smith.