From a murder at the United Nations to a climactic battle on the giant stone faces of four U.S. presidents, North by Northwest has been thrilling audiences with its improbable but highly entertaining story for nearly 60 years. Released in 1959, it was one of a string of hits for Alfred Hitchcock, who had just scored with The Man Who Knew Too Much and Vertigo and would next strike gold with Psycho. Watch out for that crop duster and enjoy these behind-the-scenes facts about an enduring classic. 

1. IT WAS CONCEIVED WHILE ITS WRITER AND DIRECTOR WERE SUPPOSED TO BE WORKING ON SOMETHING ELSE.

MGM hired Ernest Lehman (Sweet Smell of Success) to write the movie version of a novel called The Wreck of the Mary Deare, with Alfred Hitchcock assigned to direct. But Lehman got stuck on the adaptation and told Hitch he needed to find a new writer. Hitchcock, who liked working with Lehman, said, "I have this other idea ..." He'd been working on a story where a man is mistaken for a spy (who turns out not to exist), and about doing a chase sequence across Mount Rushmore. Hitchcock and Lehman developed North by Northwest from there, but neglected to tell MGM that they'd changed courses. When the studio bosses found out, they wisely let Hitch and Lehman do their own thing and reassigned The Wreck of the Mary Deare, which came out a few months after North by Northwest.

2. THE MOVIE WOULDN'T HAVE HAPPENED WITHOUT BERNARD HERRMANN.

The legendary film composer, a Hitchcock collaborator since 1955's The Trouble with Harry, is the one who introduced Hitchcock to Ernest Lehman, thinking they'd hit it off. They did. 

3. JAMES STEWART WANTED TO PLAY THE LEAD.

Stewart had been in four Hitchcock movies at this point, and he wanted North by Northwest to be the fifth. But while Hitch loved him, he didn't think he was right for the glibly debonair Roger Thornhill. He wanted Cary Grant for the part. Not wanting to hurt Stewart's feelings, Hitchcock waited until Stewart was committed to another film (Bell, Book and Candle) before casting the role. 

4. CARY GRANT HAD NO IDEA WHAT WAS GOING ON.

The star found the screenplay baffling, and midway through filming told Hitchcock, "It's a terrible script. We've already done a third of the picture and I still can't make head or tail of it!” Hitchcock knew this confusion would only help the film—after all, Grant's character had no idea what was going on, either. Grant thought the film would be a flop right up until its premiere, where it was rapturously received. 

5. PART OF IT WAS SHOT SECRETLY.

You wouldn't expect Hitchcock to have to sneak around, but even the Master of Suspense was no match for the United Nations, which did not allow filming at its New York headquarters, not even in the plaza outside. So to get the shot where Grant walks into the building, Hitchcock hid a camera in a nondescript truck and filmed in secret from across the street. 

6. ALFRED HITCHCOCK OFFENDED THE POLICE.

Cinematographer Robert Burks recalled how the director, frustrated with the inefficiency and costliness of paying for police protection again and again when shooting on location, referred to New York's finest as "New York's worst" in an interview. Well, when the crew arrived at their next location, The Plaza Hotel, there was no police protection. That's what you get, Hitch.

7. ONE LINE OF DIALOGUE WAS CENSORED.

During Cary Grant and Eva Marie Saint's first meeting on the train, she says, "I never discuss love on an empty stomach." But as you can see pretty easily if you watch her mouth, what she actually said was, "I never make love on an empty stomach." This was considered too saucy for a respectable movie, and Saint re-dubbed the line.

8. DON'T WORRY—GRANT WAS NOWHERE NEAR ANY CROP DUSTERS.

The crop duster plane was filmed separately (out near Bakersfield, California, not Indiana). Then Grant was filmed on a studio set diving into a fake ditch while the plane footage unspooled on a screen behind him. Hollywood magic! (No crops were harmed.)

9. THE INFAMOUS INNUENDO AT THE END WAS ALL HITCHCOCK.

One of the things North by Northwest is famous for is its concluding shot of a train entering a tunnel, which serves as a visual pun for the main characters' planned night of romance. Hitchcock considered it one of his finest, naughtiest achievements. And he gets all the credit, too: Lehman's screenplay just ended with "the train heads off into the distance," or words to that effect. "There's no way I can take credit for [the tunnel]," Lehman said, adding: "Dammit."

10. THE PEOPLE IN CHARGE OF MOUNT RUSHMORE WERE NOT AMUSED.

The U.S. Department of the Interior was (and is) very careful about preserving the sanctity of the Mount Rushmore monument in South Dakota. Hitchcock was given permission to film on site, but only if he promised not to depict any acts of violence taking place on the presidents' faces, or to let his actors run around disrespectfully on the heads. Well, just before the Mount Rushmore shoot was scheduled to begin, Hitchcock described his intentions to a local newspaper reporter in a way that suggested he was going to let his cast frolic on Lincoln's face after all. Learning of this, the Interior Department yanked Hitchcock's permit on the grounds of "patent desecration."

Hitch and company spent a day filming in the parking lot and in the memorial's cafeteria (where Eva Marie Saint "shoots" Cary Grant), and got plenty of footage of the memorial (without actors) from various angles. The bulk of the climactic scene was shot on a very realistic mock-up of Mount Rushmore in Los Angeles—but this proved problematic as well, as Hitchcock's team did such a good job that people believed the climax really had been filmed on Mount Rushmore (a misconception that Hitch happily encouraged). To counter this, the Interior Department demanded that MGM remove the credit at the end of the film thanking them for their cooperation, since, in fact, nearly everything Hitchcock had done had been against their wishes. 

11. THE MOVIE TOOK LONGER THAN EXPECTED TO MAKE, BUT GRANT DIDN'T MIND.

That's because in addition to his $450,000 salary ($3.7 million in 2016 dollars) and a share of the profits, Grant was paid $5000 (adjusted for inflation: $41,000) per day for every day the production ran over schedule. And it ran way over schedule: shooting hadn't even begun yet when Grant's seven weeks were up and the daily bonuses started kicking in. This lasted for 78 days, or $390,000 worth (adjusted for inflation: $3.2 million).

12. THE TITLE DOESN'T REALLY MEAN ANYTHING.

Some people have assumed "north by northwest" is a reference to a line from Hamlet: "I am but mad north-northwest: when the wind is southerly, I know a hawk from a handsaw." But Hitchcock and Lehman said it had nothing to do with that. By Lehman's account, it was much simpler: he noticed that the action started in New York, then moved to Chicago, South Dakota, and (in an earlier draft) Alaska—a northwesterly direction. "North by northwest" isn't a real compass direction (though northwest by north is); it is therefore symbolic of the film's improbable, unpredictable plot. 

13. SOME PEOPLE THINK HITCHCOCK HAS A SECOND CAMEO—IN DRAG.

The director's trademark cameo is at the beginning of the film, as he tries to board a bus just as its doors are closing. But some 44 minutes into the movie, there is a female train passenger who some fans think is Hitchcock in disguise. It certainly does look like him. But while Hitch wasn't above dressing in drag for the sake of a joke, he was more rotund than this woman, who seems to have merely been endowed with his face. 

Additional sources:
DVD bonus materials
American Film Institute