You do not need a passport, if you are a Canadian citizen, however, along with your driver's license, you will need your birth certificate or other approved documentation to prove your citizenship
At this point passports are still not required. You will, however, have to produce a government-issued photo ID (for instance a driver’s license) together with proof of citizenship (e.g. a copy of your birth certificate or naturalization certificate).
Of course if you have a passport or a NEXUS, SENTRI or FAST card - those are "one size fits all" documents - and can be used to meet both the ID and citizenship requirements.
MTO is lobbying US to accept the new more secured (20+ features) driver licence as acceptable proof of status for land entry points. As passport for land entry points would hamper commerical import/export, particularly @ Windsor with the Auto parts.