CNR grain movements during October hit a one-month record of 2.8 million metric tonnes.
The previous record for one month was 2.7 million metric tonnes, set in April this year.
Moving grain this fall has been beset by challenges from cold wet weather delaying grain deliveries and leaving rail capacity under-utilized.
CN officials attributed improved volumes to investment in new hopper cars and a more modern locomotive fleet.
So far this year CN has moved 6.7 million metric tonnes of grain.