America's marquee marathon will be the centre of attention once again.

A new feature-length documentary film about the 120-year-old Boston Marathon is in the works. Its creators say Boston will go beyond the 2013 bombings to retrace the iconic footrace's first steps in 1897.

Film Boston Marathon Documentary

Joan Benoit wins the 1983 Boston Marathon in record time for the women's division. A new feature-length documentary will cover the 2013 bombings but focus on the marathon's historical moments. (The Associated Press)

"Over the years, the Boston Marathon has had so many extraordinary stories of people achieving and accomplishing things," said producer Megan Williams, an Oscar-nominated filmmaker. "It's like looking at cultural and social change over the last century through the lens of this major sporting event."

The documentary joins a growing number of projects involving the well-known race.

Two feature films including one starring Mark Wahlberg, a stage play and an HBO documentary are also in production. But those projects will focus on the 2013 finish line attacks that killed three spectators and wounded more than 260 others.

The makers of Boston say it won't ignore the dark events of 2013, but will cast a larger spotlight on how the city and its namesake race bounced back.

The movie tentatively is set to premiere in April 2017 in conjunction with the 121st edition of the race.

John Hancock Financial, the marathon's principal backer, has signed on as the film's title sponsor, though Williams said she's still working to raise half of the project's $2 million budget.