JEFFERSON CITY, Mo. – Having just learned to read, 5-year-old Taylor Ray was naturally curious about the billboard in plain view from his parents’ vehicle along Interstate 70.

“Dad, what is ‘XXX’?” Jim Ray recalled his son asking.

“I’ve tried to explain to him that it’s something for adults that he’ll understand when he’s older,” Ray said.

That answer satisfied Taylor for about a mile, until the family drove past a similar sign.

“It’s completely unavoidable,” Ray said. “The signs refer to toys and novelties. Those things are going to catch his attention.”

The abundance of outdoor sex advertisements also has caught the attention of Missouri legislators, who are aggressively trying to cut down on the signs.

Separate bills approved by the state House and Senate would ban most highway billboards for businesses where workers appear nude or where more than 10 percent of the store space is used to display pornography.

Sexually oriented businesses located within one mile of a highway would be allowed just two onsite billboards: one with the name, address, phone number and operating hours of the business, the other warning minors to keep out.

Billboards are frequent targets for lawmakers around the country. Earlier this year, the Wyoming House defeated an attempt to reduce the size of new roadside billboards. In Utah, proposed legislation would take away some rights of local governments’ to regulate billboards. And commissioners of Clark County, Nev. – home to Las Vegas – are drafting an ordinance that could ban roadside billboards indefinitely.

Missouri highways are lined with more than 12,000 billboards, according to the Department of Transportation. No official statistics are kept regarding content, but one lawmaker counted 45 sex-themed billboards along a 120-mile stretch of Interstate 70 between Kansas City and Columbia.

“We need to make sure when we have families driving down the road that we don’t have to worry about the children saying, ‘What’s “XXX” or “totally red hot nude”?’ ” said Democratic Rep. Trent Skaggs, one of the legislation’s sponsors.

The Missouri bill is patterned after a similar law in New Jersey that also allows just two signs – one for identification and one telling minors to stay out – for all sex-related businesses. A group of businesses there sued the state, claiming the law violated the First Amendment right to free speech.

In 1998, the New Jersey Supreme Court upheld the law, saying the state had an interest in protecting the welfare of minors and reducing crime.

But Richard Hudson, a research attorney with the Nashville, Tenn.-based First Amendment Center at Vanderbilt University, said Missouri’s restrictions would face an uphill battle in court.

“To just simply restrict certain billboards based on speech, there will be high First Amendment hurdles,” Hudson said.

Owners and patrons of the sex-themed businesses also contend the Missouri legislation would violate free-speech rights.

Motorists traveling Missouri highways had mixed reactions to the legislation.

Jeff Trampleasure of Wentzville said the billboards made him dread the day he’ll have to explain the sexy pitches to his children.

“I think it’s trash,” Trampleasure, 27, said.