Los Angeles / New York - Matt Damon sci-fi thriller Elysium, the story of an elite space outpost locked in battle with poor invaders from Earth, won a tight box office race among four new films at U.S. and Canadian theaters.
Elysium grabbed $30.5m in domestic ticket sales from Friday through Sunday, edging Jennifer Aniston comedy We're the Millers, which took in $26.6m.
Walt Disney's animated movie Planes took the third slot with $22.5m, according to studio estimates. Fantasy movie Percy Jackson: Sea of Monsters landed fourth with $14.6m.
Elysium portrays two worlds in the year 2154 - a diseased and overpopulated Earth, and Elysium, a space station where the elite live far from the seething masses.
Damon stars as Max, a blue-collar worker with a criminal past who needs medicine from Elysium to survive. Jodie Foster plays the Elysium defence secretary bent on keeping Max and all other illegal immigrants out.
Planes, a spin-off of Walt Disney's Pixar franchise Cars, features the voice of Dane Cook as a crop duster with a fear of heights. The movie was produced by the DisneyToons studio and originally planned as a direct-to-DVD release.
In We're the Millers, Aniston plays a stripper enlisted by a small-time pot dealer (Jason Sudeikis) to pose as his wife when he puts together a phony family to help him smuggle marijuana into the United States.
Percy Jackson: Sea of Monsters, a sequel to a 2010 release, is based on a series of books about a boy with special powers. In the new film, the boy, played by Logan Lerman, joins his friends on a quest for a golden fleece that will save their home.
Sony's movie studio distributed Elysium. Warner Bros, a unit of Time Warner, released We're the Millers. Percy Jackson was distributed by 20th Century Fox, a unit of 21st Century Fox.