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| August 9 (preliminaries and finals)|
The women's 400 metre freestyle competition of the swimming events at the 1971 Pan American Games took place on 9 August. The last Pan American Games champion was Debbie Meyer of US.
This race consisted of eight lengths of the pool, with all eight being in the freestyle stroke.
Swimming at the 1971 Pan American Games – Women's 400 metre freestyle Wikipedia
All times are in minutes and seconds.
The final was held on August 9.