Just like for dogs, using a closed and leak-proof carrier is the only way to take your cat on Amtrak. Your cat must be kept in the carrier at all times and the carrier must be placed under your seat. You must never leave your cat alone during your Amtrak train trip.
Your cat carrier (which counts as one carry-on luggage under Amtrak’s pet policy) can be soft-sided or hard-sided and must not exceed the following dimensions: 19 inches in length, 14 inches in width, and 10.5 inches in height.