Late-Summer Sleeper District 9 Takes Weekend Box Office

District 9 won the top spot at the box office in its opening weekend, as the alien thriller drew more than $37 million, which topped second- and third- place finishers G.I. Joe: The Rise of Cobra ($22.5 million) and The Time Traveler's Wife ($19.2 million).

The film's surprise success, according to Deadline Hollywood Daily, can be attributed to a smart, grassroots marketing campaign -- consisting of bus benches warning the seats are for humans only -- from director Neill Blomkamp and producer Peter Jackson.

With the $37 million weekend, District 9 -- a story about aliens forced by humans to live in a South African ghetto -- has already taken in $7 million than its $30 million production cost.