By Lisa Richwine

LOS ANGELES (Reuters) - A big-screen version of classic Dr. Seuss children's book "The Lorax" rang up a massive $70.7 million in U.S. and Canadian ticket sales over the weekend, the biggest movie debut so far this year.

The popularity of the 3D animated "Lorax" far exceeded industry forecasts and helped lift total box-office receipts ahead of last year for the ninth weekend in a row.

Danny DeVito provides the voice of the small orange Lorax who guards the trees in the film based on Seuss' 1971 book about preserving the environment.

In the movie, Zac Efron provides the voice for a 12-year-old boy trying to win the heart of a young girl, voiced by Taylor Swift. Along the way, he discovers the story of the Lorax.

Families turned out in force for the film, which cost $70 million to produce, and audiences gave it an "A" rating on average in polling by survey firm CinemaScore. Pre-weekend forecasts had suggested an opening as high as $50 million.

"I couldn't be more excited," Nikki Rocco, president of distribution for Universal Pictures, said of the debut weekend tally. The movie satisfied "the need for a family film in the marketplace," she said.

About 8 percent of sales came from giant IMAX screens, and 52 percent came from theaters equipped for 3D. Both formats command higher ticket prices.

Before this weekend, the year's highest debut belonged to love story "The Vow," with $41.2 million.

The weekend's second-place film, "Project X," also beat projections, debuting with $20.8 million at North American (U.S. and Canadian) theaters from Friday through Sunday.

The teen-oriented comedy tells the story of three high school students who plan an epic party that spins out of control. The low-budget movie without big-name stars, which cost $12 million to make, drew in its target audience of young males.

Marketing on Twitter helped get people talking on the social networking site and "propelled this movie well past anyone's expectations," said Jeff Goldstein, executive vice president of domestic distribution for Warner Bros.

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Overall domestic ticket receipts beat the same weekend last year by nearly 26 percent, the ninth straight weekly increase, according to the box office division of Hollywood.com. So far, 2012 ticket sales are running 19 percent ahead of last year.

In third place for the weekend, military drama "Act of Valor" pulled in $13.7 million. The movie released by privately held Relativity Media has grossed $45.2 million domestically since its release last weekend.

Rounding out the top five on domestic charts, Denzel Washington thriller "Safe House" pulled in $7.2 million and Tyler Perry drama "Good Deeds" grossed $7.0 million.

Fresh off its Oscar wins, black-and-white silent film "The Artist" gained 34 percent from last weekend to pull in $3.9 million domestically. The Weinstein Co. expanded the movie to 1,756 theaters from 966 after the film won five Academy Awards including best picture. The film's total domestic take now stands at $37.1 million since its limited release in November.

The studio is "very happy with these numbers," said David Glasser, Weinstein's chief operating officer. "You have to remember we have a silent, black-and-white movie," he said.

Comcast Corp's Universal Pictures released "Dr. Seuss' The Lorax" and "Safe House." "Project X" was distributed by Time Warner Inc unit Warner Bros. Lions Gate Entertainment released "Good Deeds."

(Reporting By Lisa Richwine; editing by Todd Eastham)