"Dr. Seuss' The Lorax" raked in $70.7 million in its first weekend to score the biggest box-office debut of the year by far.
The 3-D animated family film from Universal Pictures, featuring the voices of Danny DeVito, Zac Efron and Taylor Swift, is based on Seuss' cautionary fable about the importance of preserving the environment.
Coming in second place with a strong debut of its own was the R-rated "Project X," about a trio of high school misfits who throw a raging party in hopes of becoming popular.
The Warner Bros. comedy made about $20.8 million, according to Sunday studio estimates.
Before this, "The Vow" had the best debut of 2012 with $41.2 million.
Last week's No. 1 movie, "Act of Valor," dropped to third place with $13.7 million.