The movie updates the 1951 tale of an alien and his giant robot enforcer who come to Earth with a warning about the consequences of humanity's destructive nature.
"Audiences are moving to see `The Day the Earth Stood Still.' It's a visually stunning movie with timely issues everybody on this planet can relate to," said Fox distribution executive Chris Aronson. "Basically, how we treat each other and how we treat this planet that we call home."
The Warner Bros. holiday romp "Four Christmases" slipped to second place with $13.3 million. The Reese Witherspoon-Vince Vaughn comedy raised its three-week total to $88 million.
Another seasonal tale, Overture Films' "Nothing Like the Holidays," opened a weak No. 7 with $3.5 million. The movie features John Leguizamo, Debra Messing and Alfred Molina in the story of a Chicago family's holiday reunion.
The overall box office plummeted compared with the same weekend last year, when "I Am Legend" opened with $77.2 million and "Alvin and the Chipmunks" debuted with $44.3 million. This weekend's top 12 movies took in $83.3 million, down 45 percent from a year ago.
"This was predestined to be a down weekend given the incredible one-two punch of 'I Am Legend' and 'Alvin,"' said Paul Dergarabedian, president of box-office tracker Media By Numbers. "There was no way this weekend could measure up."
A rush of films opened with big numbers in limited release to qualify for the Academy Awards.
Miramax's "Doubt" pulled in $525,030 in 15 theaters, averaging $35,002 a cinema, compared with $8,708 in 3,560 locations for "The Day the Earth Stood Still." The film stars Meryl Streep, Philip Seymour Hoffman and Amy Adams in a war-of-wills drama between an old-school nun and a progressive priest.
Clint Eastwood's "Gran Torino" played in six locations and took in $284,000 to average $47,333. The Warner Bros. film stars Eastwood as a bigot who becomes an unlikely protector for his immigrant neighbors against street thugs.
The Weinstein Co. drama "The Reader" rang up $170,000 in eight theaters for a $21,250 average. The Holocaust-themed story stars Kate Winslet as a former concentration camp guard standing trial years later.
Steven Soderbergh's two-part, four-hour-plus film biography "Che" took in $60,100 in two cinemas to average $30,050. The IFC Films release stars Benicio Del Toro as Latin American revolutionary Che Guevara.
Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC. Final figures will be released Monday.
1. "The Day the Earth Stood Still," $31 million.
2. "Four Christmases," $13.3 million.
3. "Twilight," $8 million.
4. "Bolt," $7.5 million.
5. "Australia," $4.3 million.
6. "Quantum of Solace," $3.8 million.
7. "Nothing Like the Holidays," $3.5 million.
8. "Madagascar: Escape 2 Africa," $3.3 million.
9. "Milk," $2.6 million.
10. "Transporter 3," $2.3 million.
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Universal Pictures, Focus Features and Rogue Pictures are owned by NBC Universal, a unit of General Electric Co.; Sony Pictures, Sony Screen Gems and Sony Pictures Classics are units of Sony Corp.; DreamWorks, Paramount and Paramount Vantage are divisions of Viacom Inc.; Disney's parent is The Walt Disney Co.; Miramax is a division of The Walt Disney Co.; 20th Century Fox, Fox Searchlight Pictures and Fox Atomic are owned by News Corp.; Warner Bros., New Line, Warner Independent and Picturehouse are units of Time Warner Inc.; MGM is owned by a consortium of Providence Equity Partners, Texas Pacific Group, Sony Corp., Comcast Corp., DLJ Merchant Banking Partners and Quadrangle Group; Lionsgate is owned by Lionsgate Entertainment Corp.; IFC Films is owned by Rainbow Media Holdings, a subsidiary of Cablevision Systems Corp.