Dinosaurs, superheroes and rappers have boosted summer box office receipts in the United States, setting 2015 on course to be the biggest grossing year in movie history.

"It's not a record summer but we're still on track for what could be the biggest box office year in theaters," said Paul Dergarabedian, a senior media analyst at Rentrak, which tracks viewership for the movie industry.

"It could be the first 40-billion-dollar year ever worldwide... and that's pretty impressive considering the competition by the small screen including Netflix, Hulu and HBO."

Smash hits like "Jurassic World," "Avengers: Age of Ultron" or "Straight Outta Compton" largely contributed to the estimated $4.4 billion Hollywood is expected to rake in this summer in North America.

And the cash registers are expected to keep ringing through the end of the year.

"In 2013, we had $4.75 billion in receipts for the summer. It should come to $4.5 billion this year," said Patrick Corcoran, spokesman for the US National Association of Theatre Owners.

Dergarabedian attributed the box office uptick to the diverse slate of movies on offer and the need for audiences to seek entertainment outside the home.

"Jurassic World," the long-awaited fourth installment in the blockbuster dinosaur franchise launched by Steven Spielberg in 1993, has already taken in $643 million in North America and $1.6 billion globally, putting it right behind "Avatar" and "Titanic."

"Avengers: Age of Ultron" has for its part grossed $457.7 million in North America and $1.4 billion worldwide.

Animated films "Inside Out" and "Minions," musical comedy sequel "Pitch Perfect 2" and music biopic "Straight Outta Compton," which charts the rise and fall of the iconic hip-hop group N.W.A., also contributed to this summer's box office success.

Beyond the quality of the movies on offer this summer, Corcoran said movie theaters are also going all out to draw in audiences.

"In the last decade and a half, there has been some enormous changes in the cinema experience -- in auditoriums, recliner seats, very large screens, food and alcohol serving," he said.

"3D has also been a useful addition to box office attendance," he said.

"And the mix of movies means there is a little something for everyone."