Batman can't be stopped. For the fourth weekend the superhero's sixth film The Dark Knight led at the US box office.

The movie took in $26 million over the weekend, grossing more than $441 million since opening on July 14.

Only seven films have ever topped the $400 million in the US and Canadian market, led by Titanic in 1998, which earned $600 million.

The Dark Knight is now the number-three highest grossing film ever behind 1977's Star Wars ($461 million).

Action comedy Pineapple Express was second at the box office on the weekend, earning $22.4 million.

The movie about a stoner and his drug dealer, a murder and a unique strain of marijuana stars Seth Rogen, James Franco and Rosie Perez.

The Mummy: Tomb of the Dragon Emperor, staring Brendan Fraser, brought in $16 million for third place in its second weekend.

Teen friendship comedy The Sisterhood of the Traveling Pants 2 was fourth with $10.8 million, and Will Ferrell's Step Brothers rounded out the top five with $8.9 million.