The tale of a band of Spartan warriors that repels the initial attacks by a massive invading Persian army generated the third biggest opening for an R-rated film behind The Matrix Reloaded ($91m) and The Passion Of The Christ ($83m).
Approximately $3.4m of the total came from 62 IMAX screens. Zack Snyder directed 300, which stars Gerard Butler, Lena Headey and Rodrigo Santoro and was projected to open in the $40m range.
The film's prospects internationally, where sword and sandal epics tend to perform strongly, now look even more enticing and the film opens in the UK in a couple of weeks.
Disney's comedy Wild Hogs fell to second after last weekend's number one release and raised its tally by $28m to $77.4m.
In fourth place Sony's Ghost Rider crossed $100m in its fourth weekend as $6.8m raised the cumulative total to $104.1m.
Paramount's Norbit is inching its way to $100m and ranks seventh on $88.3m after five. Samuel Goldwyn and Roadside Attractions' historical drama Amazing Grace returned to the top 10 in its third weekend on $2.5m for $11.4m.
Paramount Vantage's Black Snake Moan exited the top 10 in its second weekend and ranks 11th on $7.3m.
Next weekend's wide releases are Sony Pictures' thriller Premonition, which launches under the Tristar Pictures label and stars Sandra Bullock and Julian McMahon; and Universal's horror title Dead Silence with Ryan Kwanten and Amber Valletta.
Estimated Top Ten North America Mar 9-11, 2007
Film (Distributor)/International distribution/Estimated weekend gross/Estimated total to date
1 (-) 300 (Warner Bros) WBPI $70m -
2 (1) Wild Hogs (Buena Vista) BVI $28m $77.4m
3 (4) Bridge To Terabithia (Buena Vista) Summit $6.9m $67m
4 (3) Ghost Rider (Sony) SPRI $6.8m $104.1m
5 (2) Zodiac (Paramount) PPI $6.8m $23.7m
6 (5) The Number 23 (New Line) NLI $4.3m $30.5m
7 (6) Norbit (Paramount) PPI $4.3m $88.3m
8 (7) Music And Lyrics (Warner Bros) WBPI $3.8m $43.8m
9 (10) Breach (Universal) Kimmel Intl $2.6m $29.1m
10 (11) Amazing Grace (Samuel Goldwyn/Roadside Attractions) Lakeshore Entertainment $2.5m $11.4m