Strong growth overseas helped to make up for a box-office slump in the U.S. and Canada last year, according to data released Wednesday by the Motion Picture Association of America.

Global box-office sales grew 5% in 2017, to $40.6 billion, the Hollywood trade group said, driven entirely by 7% surge overseas, to $29.5 billion. Domestically, box office was down 2%, to $11.1 billion, reflecting its status as what the MPAA called a “mature” market.

Box...