That was nearly twice the forecast by distributor Warner Bros., whose head of distribution, Dan Fellman, said he had hoped the movie might deliver a $30 million debut.
"Women power," Fellman said. "It was outstanding this weekend."
Analysts had figured Paramount's "Indiana Jones and the Kingdom of the Crystal Skull" might stay atop the box office heap, but it slipped to second place with $46 million in its second weekend. "Indiana Jones" raised its 11-day domestic total to $216.9 million.
"Sex and the City" put up numbers never before seen for a movie aimed mainly at women, who do not tend to rush out in huge numbers for opening weekends the way males do.
"Sex and the City," released under Warner's New Line Cinema banner, had the best debut ever for an R-rated comedy, topping the $45.1 million opening of "American Pie 2."
The movie landed at No. 5 on the all-time list among R-rated films, behind "The Matrix Reloaded" ($91.8 million), "The Passion of the Christ" ($83.8 million), "300" ($70.9 million) and "Hannibal" ($58 million).
"This is a blockbuster for women. This was to women what `Indiana Jones' and `Star Wars,' let's say, are to men," said Paul Dergarabedian, president of box office tracker Media By Numbers.
The movie picks up four years after the series finale, in which Parker's Carrie Bradshaw and her Manhattan buddies left behind their randy ways to settle into monogamous relationships. In the film, they deal with family and commitment issues while still flaunting their bawdy humor and trendy sense of style.
Hollywood skeptics had doubted the commercial prospects for a movie adaptation of "Sex and the City," which ended its six-year run in 2004. Originally airing on premium cable channel HBO, the show had a loyal but limited fan base and held little appeal for young males, the backbone of the box office.
However, "Sex and the City" mania grew as the movie's release approached, with many women organizing girls-night-out parties to see it with friends on opening day Friday.
"That's why Friday was quite a frenzy," Fellman said. "There were women that came in and bought out entire theaters in advance and invited all their friends."
Women made up 85 percent of the audience on Friday, Fellman said.
The movie pulled in $26.9 million on Friday. On Saturday, however, it took a steep drop with ticket sales dwindling to $17.7 million. Most big films take in more money on Saturday than Friday, so the decline was a sign that the audience for "Sex and the City" could dry up quickly.
Still, the film was on its way to becoming a $100 million hit that could spawn more sequels.
The weekend's other new wide release, Universal's fright flick "The Strangers," debuted solidly at No. 3 with $20.7 million. It stars Liv Tyler and Scott Speedman as a couple terrorized by masked invaders at their vacation home.
Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC. Final figures will be released Monday.
1. "Sex and the City," $55.7 million.
2. "Indiana Jones and the Kingdom of the Crystal Skull," $46 million.
3. "The Strangers," $20.7 million.
4. "Iron Man," $14 million.
5. "The Chronicles of Narnia: Prince Caspian," $13 million.
6. "What Happens in Vegas," $6.9 million.
7. "Baby Mama," $2.2 million.
8. "Speed Racer," $2.1 million.
9. "Made of Honor," $2 million.
10. "Forgetting Sarah Marshall," $1 million.