The premiere was viewed as healthy but unremarkable in a summer season whose newcomers often open with two or three times as much money.
The Paramount Pictures film largely features a cast of young newcomers. The story centers on teen filmmakers and an alien entity that escapes from a wrecked train.
"The movie was never conceived to be a blockbuster, tent-pole film opening to $60 or $70 million," said Don Harris, head of distribution for Paramount.
"Super 8" bumped the previous weekend's No. 1 movie, "X-Men: First Class," which slipped to second place with $25 million. "First Class" raised its domestic total to $98.9 million.
The weekend's other new wide release, Relativity Media's family flick "Judy Moody and the NOT Bummer Summer," opened weakly at No. 7 with $6.3 million. The movie follows a young girl's wacky summer adventures.
1. "Super 8," $37 million ($6.7 million international).
2. "X-Men: First Class," $25 million.
3. "The Hangover Part II," $18.5 million ($38.3 million international).
4. "Kung Fu Panda 2," $16.6 million ($56.5 million international).
5. "Pirates of the Caribbean: On Stranger Tides," $10.8 million ($41.1 million international).
6. "Bridesmaids," $10.2 million.
7. "Judy Moody and the NOT Bummer Summer," $6.3 million.
8. "Midnight in Paris," $6.1 million.
9. "Thor," $2.4 million.
10. "Fast Five," $1.7 million ($5.9 million international).
The Associated Press contributed to this report.