The two teen-age girls were in a car that struck a telephone pole in Valley Park, Mo., at 35 miles an hour.

Neither was wearing a seat belt, but air bags in their car protected them. They walked away from the accident, one with a broken nose, the other with a sore shoulder.

In Westport, Conn., Melanie Stephenson was rounding a curve on a rain-slicked road, lost control, and rammed head-on into a propane tanker-truck, destroying her car.

An air bag in her car, inflated in a fraction of a second, saved her from almost certain death, police said. Thanks to the bag and her shoulder and lap belt, she escaped with bruised knees.

The two accidents were 12 years apart -- June 1973 in Valley Park and June 1985 in Westport.

They are two small but noteworthy benchmarks in the twisted history of air bags, a long, sorry chapter of conflict between government regulators, auto safety advocates and the leading American industry. The story has some lessons for business and its regulators and critics today.

Air bags -- a vital passenger safety device in serious head-on crashes -- have been available in a technological sense since the early 1970s, as the Valley Park accident makes plain.

General Motors Corp. installed air bags on some 10,000 luxury cars as an option during the mid-'70s, but dropped the program after Edward Cole's retirement as president in September 1974. Cole was the chief air bag booster.

After GM quit, a decade went by before another American auto maker offered the air bag option. This time, it was the Ford Motor Co., which equipped 7,400 1985-model sedans with air bags and sold them to the government and a few corporate fleets.

Melanie Stephenson, an employe of The Travelers Cos., was driving one of the Fords.

Next March, the public gets another chance to buy air bags from an American producer. Ford will offer the air bag option on the driver's side of four-door Topaz and Tempo models, at a suggested retail price of $815. And with Mercedes Benz and other European carmakers offering or about to offer air bags, the battle appears over.

True, the initial price will be steep for many Ford buyers, but as sales grow, the price will come down, and the government estimates that when production reaches 1 million units, the price will have dropped to $320 -- no more than an average AM/FM radio and cassette player. It will be a bargain for people like Melanie Stephenson.

The question that a legion of Detroit's auto executives, government regulators, congressional politicians and consumer activists should be asking is why a decade was wasted in wrangling over this safety device.

The epitaph for that decade is offered by author Brock Yates, in his book, "The Decline and Fall of the American Automobile Industry."

"The 1970s was an absurd decade during which government and industry butted heads and the general public gained little," he said.

Throughout the 1970s, according to Yates, Detroit's auto executives were insular, lethargic about competition and truculent about government regulation.

"One conclusion some may reach is, 'If the government only hadn't gotten involved, the industry would have done it much sooner.' I have a hard time believing that," said Joan Claybrook, a leading consumer and safety advocate who crossed the street to become administrator of the National Highway Traffic Safety Administration during the Carter years.

Her evidence is the industry's record of resistance and obstruction to the government's air bag efforts after Cole left GM. GM continues to battle air bag regulation, she noted, preferring the option of mandatory seat belt laws that Transportation Secretary Elizabeth Hanford Dole has offered.

"They're so intent on not allowing the government to tell them what to do -- even when it affects the whole society -- that they're blind to the marketing advantages of seat belts," Claybrook said.

For its part, the auto industry felt beseiged by government regulators, whose demands shifted with the political winds, playing havoc with Detroit's struggles to face up to the emerging Japanese competition.

"For quite awhile in the '70s, this corporation had to take every guy who could draw a straight line and put him on emissions, fuel economy and safety. We had very little people left over for our future," GM Chairman Roger Smith said in an interview this year. "It was the dumbest way to do anything you can ever imagine."

The plea of Chrysler Chairman Lee A. Iacocca in 1971, when he was Ford's president, is preserved in President Richard Nixon's secret White House tapes. The transcription of a meeting between Iacocca, Henry Ford II and Nixon shows Iacocca telling Nixon that he wished the regulators would "cool it a little bit. You're going to break us. . . . We cannot carry the load of inflation in wages and safety in a four-year period without breaking our back. . . . " Couldn't the government pay some attention to the industry's problems, Iacocca asked.

Iacocca and Ford won Nixon over, but the air bag regulation see-sawed up and down as administrations changed.

Late in 1976, William T. Coleman, then the secretary of Transportation, decided not to require air bags or other automatic passenger protection systems, in favor of a "demonstration" program to test the technology and public reaction to the systems.

In January 1977, the last month of the Ford administration, Coleman arranged with GM, Ford and Mercedes to undertake a voluntary program to equip 62,250 cars with air bags.

Coleman's decision was knocked out by the Carter administration, initiating a regulatory and legal struggle too complex to recount here.

But to one leading air bag proponent -- Brian O'Neill, president of the Insurance Institute for Highway Safety -- Coleman's compromise looks pretty good from the vantage point of nearly a decade.

"I suppose one of the lessons I've learned from this is that regulation isn't necessarily the best way to move foward, because it's taken us so many years and so many regulations," said O'Neill. Now that air bags are arriving, it's competition, not regulation, that's responsible, he says.

"I think the safety activists and insurance companies have kept the idea of air bags alive when it could have easily died," said O'Neill. But their all-or-nothing demands also contributed to the seige mentality that helped keep the air bag on the shelf.