| Final 19:10 | time |   | gap | L | React. | 50m |  | 1. Chantal Van Landeghem |  CAN | 53.83s | PR | 3 | 0.79 | 28.04s | 3. |  | 2. Natalie Coughlin |  USA | 54.06s | 0.23 | 4 | 0.66 | 28.32s | 2. |  | 3. Arianna Vanderpool-Wallace |  BAH | 54.15s | 0.32 | 5 | 0.66 | 28.69s | 1. |  | 4. Michelle Williams |  CAN | 54.55s | 0.72 | 7 | 0.79 | 28.34s | 4. |  | 5. Larissa Martins |  BRA | 54.61s | 0.78 | 2 | 0.71 | 28.31s | 5. |  | 6. Graciele Herrmann |  BRA | 55.01s | 1.18 | 8 | 0.66 | 28.67s | 6. |  | 7. Vanessa Garcia |  PUR | 55.26s | 1.43 | 1 | 0.69 | 28.75s | 7. |  | 8. Amanda Weir |  USA | 55.73s | 1.90 | 6 | 0.82 | 29.17s | 8. |   
| World Record: Britta Steffen (GER) 52.07s, Roma (ITA), 31.07.2009. |  | Pan American Games Record: Amanda Weir (USA) 54.46s, Santo Domingo (DOM, 11.08.2003. |  | Qualification times. Standard A: 56.91s, Standard B: 1:00.32. |   
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| Final B 19:05 | time | gap | L | React. | 50m |  | 9. Liliana Ibanez |  MEX | 55.90s |   | 4 | 0.70 | 28.70s | 3. |  | 10.Isabella Arcila |  COL | 56.37s | 0.47 | 5 | 0.72 | 29.10s | 5. |  | 11.Elisbet Gamez |  CUB | 56.84s | 0.94 | 6 | 0.70 | 29.20s | 8. |  | 12.Aixa Triay |  ARG | 56.87s | 0.97 | 3 | 0.79 | 29.65s | 4. |  | 13.Chinyere Pigot |  SUR | 57.25s | 1.35 | 2 | 0.75 | 29.93s | 6. |  | 14.Mckenna De Bever |  PER | 57.56s | 1.66 | 7 | 0.72 | 30.48s | 2. |  | 15.Ariel Weech |  BAH | 57.79s | 1.89 | 8 | 0.69 | 30.83s | 1. |  | 16.Karen Torrez |  BOL | 57.79s | 1.89 | 1 | 0.65 | 30.34s | 7. |   
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 |   |  | First 8 to Final. Next 8 to Final B.  |   
| Ranking | time | gap | L | React. | 50m | Heat |  | 1. Natalie Coughlin |  USA | 53.85s | GR | 4 | 0.67 | 28.00s | 1. | Heat 3 |  | 2. Arianna Vanderpool-Wallace |  BAH | 54.00s | 0.15 | 4 | 0.65 | 28.47s | 1. | Heat 4 |  | 3. Chantal Van Landeghem |  CAN | 54.31s | 0.46 | 5 | 0.71 | 28.32s | 2. | Heat 4 |  | 4. Amanda Weir |  USA | 54.36s | 0.51 | 5 | 0.79 | 28.16s | 2. | Heat 3 |  | 5. Larissa Martins |  BRA | 55.01s | 1.16 | 5 | 0.70 | 28.39s | 2. | Heat 2 |  | 6. Michelle Williams |  CAN | 55.29s | 1.44 | 4 | 0.76 | 28.83s | 1. | Heat 2 |  | 7. Vanessa Garcia |  PUR | 55.45s | 1.60 | 6 | 0.73 | 28.25s | 4. | Heat 3 |  | 8. Graciele Herrmann |  BRA | 55.54s | 1.69 | 3 | 0.67 | 29.00s | 3. | Heat 4 |  |  to Final B |  | 9. Liliana Ibanez |  MEX | 55.80s | 1.95 | 6 | 0.74 | 28.83s | 4. | Heat 4 |  | 10.Isabella Arcila |  COL | 56.12s | 2.27 | 3 | 0.71 | 29.11s | 3. | Heat 3 |  | 11.Alia Atkinson |  JAM | 56.29s | 2.44 | 3 | 0.70 | 29.36s | 3. | Heat 2 |  | 12.Arlene Semeco |  VEN | 56.56s | 2.71 | 7 | 0.76 | 28.97s | 7. | Heat 3 |  | 13.Aixa Triay |  ARG | 56.82s | 2.97 | 2 | 0.82 | 29.61s | 5. | Heat 3 |  | 14.Elisbet Gamez |  CUB | 56.94s | 3.09 | 2 | 0.76 | 29.41s | 6. | Heat 2 |  | 15.Chinyere Pigot |  SUR | 57.29s | 3.44 | 2 | 0.81 | 30.01s | 6. | Heat 4 |  | 16.Mckenna De Bever |  PER | 57.40s | 3.55 | 7 | 0.73 | 30.40s | 4. | Heat 2 |  | 17.Karen Torrez |  BOL | 57.49s | 3.64 | 7 | 0.62 | 30.38s | 5. | Heat 4 |  | 18.Ariel Weech |  BAH | 57.80s | 3.95 | 6 | 0.71 | 30.38s | 5. | Heat 2 |  |  eliminated |  | 19.Allyson Ponson |  ARU | 57.89s | 4.04 | 1 | 0.73 | 30.32s | 6. | Heat 3 |  | 20.Loren Bahamonde |  ECU | 58.29s | 4.44 | 1 | 0.70 | 30.21s | 8. | Heat 4 |  | 21.Ines Remersaro |  URU | 58.81s | 4.96 | 8 | 0.71 | 30.76s | 7. | Heat 4 |  | 22.Marie Laura Meza |  CRC | 58.89s | 5.04 | 8 | 0.73 | 31.11s | 8. | Heat 3 |  | 23.Karen Riveros |  PAR | 58.94s | 5.09 | 1 | 0.68 | 30.40s | 7. | Heat 2 |  | 24.Elinah Phillip |  IVB | 1:00.76 | 6.91 | 8 | 0.72 | 32.02s | 8. | Heat 2 |  | 25.Dalia Torrez |  NCA | 1:01.48 | 7.63 | 4 | 0.62 | 32.18s | 2. | Heat 1 |  | 26.Jamaris Washshah |  ISV | 1:01.68 | 7.83 | 3 | 0.76 | 32.40s | 1. | Heat 1 |  | 27.Samantha Roberts |  ANT | 1:02.66 | 8.81 | 5 | 0.84 | 32.75s | 3. | Heat 1 |  | 28.Onika George |  GUY | 1:05.00 | 11.15 | 6 | 0.77 | 34.80s | 4. | Heat 1 |   
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| Swimmer | Q. time | Birth |  | Arianna Vanderpool-Wallace |  BAH | 54.18s | 04 MAR 1990 |  | Natalie Coughlin |  USA | 54.18s | 23 AUG 1982 |  | Michelle Williams |  CAN | 54.21s | 02 JAN 1991 |  | Chantal Van Landeghem |  CAN | 54.31s | 05 MAR 1994 |  | Amanda Weir |  USA | 54.43s | 11 MAR 1986 |  | Larissa Martins |  BRA | 54.61s | 16 FEB 1993 |  | Graciele Herrmann |  BRA | 54.76s | 01 JAN 1992 |  | Isabella Arcila |  COL | 55.87s | 11 MAR 1994 |  | Alia Atkinson |  JAM | 56.06s | 11 DEC 1988 |  | Liliana Ibanez |  MEX | 56.11s | 30 JAN 1991 |  | Vanessa Garcia |  PUR | 56.12s | 18 JUL 1984 |  | Ariel Weech |  BAH | 56.50s | 28 OCT 1991 |  | Chinyere Pigot |  SUR | 56.92s | 01 MAY 1993 |  | Aixa Triay |  ARG | 57.11s | 01 MAY 1990 |  | Elisbet Gamez |  CUB | 57.11s | 17 JAN 1997 |  | Karen Torrez |  BOL | 57.60s | 29 JUL 1992 |  | Arlene Semeco |  VEN | 57.77s | 11 JAN 1984 |  | Mckenna De Bever |  PER | 57.87s | 05 JUN 1996 |  | Loren Bahamonde |  ECU | 58.10s | 04 JUN 1987 |  | Allyson Ponson |  ARU | 58.16s | 04 DEC 1995 |  | Karen Riveros |  PAR | 58.72s | 04 DEC 1994 |  | Ines Remersaro |  URU | 59.11s | 02 DEC 1992 |  |  Standard A: 59.61s |  | Marie Laura Meza |  CRC | 59.93s | 20 NOV 1990 |  |  Standard B: 1:00.32 |  | Elinah Phillip |  IVB | 1:00.72 | 03 APR 2000 |  | Dalia Torrez |  NCA | 1:01.20 | 29 MAR 1990 |  | Samantha Roberts |  ANT | 1:02.06 | 21 APR 2000 |  | Jamaris Washshah |  ISV | 1:03.70 | 27 JUN 1997 |  | Onika George |  GUY | 1:05.03 | 02 JAN 1998 |   
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