Entering the US from Canada:
https://help.cbp.gov/app/answers/det...-residents-%2F
"
By Land and Sea (including ferries) - Canadian citizens traveling to the U.S. by land or sea are required to present one of the travel documents listed below, and may generally visit the U.S. for up to six months. CBP will accept: Canadian passport, Enhanced Driver's License/Enhanced Identification Card, NEXUS, FAST/EXPRES and SENTRI enrollment cards."
Entering Canada from the US:
http://travel.gc.ca/returning/customs/entering-canada
"Make sure you carry proper identification for yourself and any children travelling with you to help confirm your legal right to enter Canada.The Government of Canada recommends that Canadian citizens travel with a valid Canadian passport because it is the only reliable and universally accepted travel and identification document available to Canadians for the purpose of international travel.
International transportation companies such as airlines may require travellers to present a passport before boarding. Canadian citizens may face delays or may not be allowed to board the plane or other conveyance if they present other documents such as a:
- Enhanced Driver's License (EDL)/Enhanced Identification Card (EIC)
- NEXUS card (used where the program is available)
- Free and Secure Trade (FAST) card used in FAST lanes
- Canadian citizenship card
- Certificate of Indian Status
- Birth certificate in combination with either a driver's licence or a government-issued photo identification"