Admiral Wilson Boulevard is nothing more than a concrete corridor, a high-speed connection between Philadelphia and the affluent suburb of Cherry Hill, N.J. The businesses on the highway, mostly gas stations, liquor stores, discount houses and sex shops, attest to the "just passin' through" nature of the road. But as unremarkable as the boulevard appears these days, it was once the site of a historic breakthrough in motion picture exhibition.

Not that Richard Hollingshead knew, when he opened the world's first drive-in theater here on June 6, 1933, that his creation would change the movie-going (and mating) habits of several generations of Americans. It soon became obvious, however, that the 600 or so motorists who showed up at the "world's first auto movie theater" on opening night (admission 25 cents per person, maximum $1 a carload) were there not only to catch "Wife Beware," a three-year-old movie starring Adolphe Menjou, but to indulge in the kind of private acts--chatting, smoking, or sex--that were frowned upon in movie palaces.

Hollingshead, a wealthy businessman who owned a large chemical company, claimed in later years that the drive-in idea came to him while he and his family were watching a movie at home. He mounted a small screen in his driveway and then placed a projector on top of his car, so his family could watch the picture in open-air comfort. Hollingshead even experimented with a lawn sprinkler, to see if a film could be seen through a car windshield that was wet with rain.

These impromptu alfresco tests led to several years of serious research, during which Hollingshead developed a system of ramps and inclined grades which made film-watching from a car a reality. The basic idea, which was eventually patented, involved seven rows of inclined grades, which insured an uninterrupted view of the screen regardless of whether cars were arriving or leaving their places in the front rows during the showing of the film. Each aisle was 50 feet deep, and a 5 percent upgrade at the front of each row allowed for the elevation necessary to see the film without obstructions.

Hollingshead's ideas were eventually combined with the results of experiments at RCA-Victor's Camden laboratories. At about the same time Hollingshead was granted his patent, RCA engineers announced they had worked out controlled directional sound, which meant that a motorist in the last row of the theater would be able to hear the film at the same volume as those in the front rows. It was RCA that eventually provided the three six-foot-square speakers (in-car sound systems were not introduced until the 1940s) for Hollingshead's drive-in.

The forerunner of today's "passion pit" was built on a 250,000-square- foot field located about 15 minutes from downtown Philadelphia. The theater, which cost $60,000 to erect, had room for 400 cars, featured a screen that was 40 by 60 feet, a sunken projection booth located 135 feet from the screen, and more than 200 trees encircling it for ambiance. Regular shows, two per night, included selected shorts and "abridged features, with all dull or uninteresting parts removed," according to a local news report at the time. After the first week of operation, Hollingshead introduced a concession stand, which sold hot dogs, ice cream and beer.

In an interview at the time, Hollingshead (who died in 1975) claimed the drive-in would benefit several types of moviegoers. "Inveterate smokers," he said, "could smoke without offending others. Also, people could chat or even partake of refreshments brought to their cars without disturbing those who preferred silence. The drive-in welcomed the entire family regardless of the number of children. The drive-in also proved a boon to the aged and infirm. The drive-in idea virtually transformed an ordinary motor car into a private theater box."

Most of these benefits were immediately recognized by the world at large, even though the opening of Hollingshead's brainchild was greeted with a mixture of praise and skepticism. Some newspapers wondered if Detroit's boxy cars would prove adequate for the drive-in experience. Others saw it as a passing fad. And then there were those, like the editorial writer for Motion Picture Daily, who immediately noted that "the Romeos who lost out in the backseats of picture houses when West Point ushers and super-service came into the de luxe houses are waking up in a new world."

Despite immediate commercial success, Hollingshead and his theater did have to deal with some major problems. Film distributors, who saw the drive-in as a threat to movie theaters, either refused to give Hollingshead new films or charged exorbitant rental rates for old pictures.

"The first film at the drive-in was three years old and cost us $400 for four days," said Hollingshead in 1965. "The last time the film had run was in a little South Camden movie that paid $20 a week for it."

Hollingshead was also plagued by legal problems revolving around his patent. Hollingshead's company, Park-In Theaters, had the right to license and collect royalties from all drive-ins built before 1950. The first license went to a theater in Los Angeles, but by 1939, thanks to the Depression and a faddish air that hung over the idea, only about 10 drive-ins existed in the entire country. In the five years after World War II, however, nearly 5,000 were built. Most would not pay royalties to Hollingshead's company (the inventor estimated that only about 100 ever paid), and even though Park-In spent more than $250,000 in legal fees in an attempt to enforce its patent rights, it was unsuccessful. By 1950, the legal point was moot.

Aside from these problems, Hollingshead also had to deal with angry parents, many of whom felt that every time a new drive-in was built, a license for immoral conduct was being issued. "We always had a lot of criticism about kids necking," said Hollingshead, "but I've always said that I'd rather see my daughter in a drive-in than parked in a dark alley somewhere."

It was the problem with film distributors, however, that forced Hollingshead to sell his Camden drive-in to a Union, N.J., theater owner in 1935. "It was a real success in Camden," said Hollingshead, "but the high film rental rates continued to plague us. We probably never would have sold it otherwise. The man in Union who bought it had several indoor theaters in north Jersey, so he could easily get films."

Although Hollingshead never opened another theater, he remained loyal to his creation. Interviewed shortly before his death, the retired executive admitted that he and his wife occasionally attended the Main Line Drive-In near his Villanova, Pa., home. Asked what kind of movies he preferred when he ventured into the ozone, Hollingshead chuckled and said, "I like dirty movies the best."