Talk about the film started early, in August 2017, when Cruise broke his ankle performing a stunt in London, with video to prove it.
"Paramount was strategically perfect in their marketing and publicity game," said comScore senior media analyst Paul Dergarabedian.
"They showed how important a star's presence is in marketing the movie early on. Tom Cruise broke his ankle and they made that into a positive for the movie - it fed the Tom Cruise Mission: Impossible mystique."
Second place went to Mamma Mia! Here We Go Again, which fell 57 per cent in its second weekend in theatres, to earn US$15m.
Denzel Washington's The Equalizer 2 slid to third with US$14m in weekend two, and Hotel Transylvania 3: Summer Vacation took fourth with US$12.3m.
The animated Teen Titans Go! To the Movies, a feature spinoff of the Cartoon Network television show about Robin and some of the lesser-known DC superheroes, was the only major film to open against Fallout.
The Warner Bros release earned US$10.5m and landed in fifth place.
The film earned positive reviews from critics and younger audiences, but also faced a fair amount of animated competition from both Hotel Transylvania 3 and Incredibles 2, which was still going strong in its seventh weekend and headed toward the $1b mark.
As of yesterday, the Disney/Pixar sequel had earned an estimated US$996.5m globally.
But although US$10.5m might seem on the lower side, Teen Titans also cost only US$10m to produce.
"Family movies like this will play for a lot of weeks," said Warner Bros' domestic distribution president Jeff Goldstein.
"The whole objective of this movie was to work with our cousins in other Warner units for brand identification."
- AP