I don't know about Mexico but you definitely don't need one for Canada.
You do not need a passport to enter Canada.
HOWEVER...your own government will not let you back in the country unless you have a passport or a recognized equivalent (border crossing card, or approved biometric state drivers license, etc.)
You need a passport or a passport card to re-enter the US from Canada.
Depends on how you travel to Canada. If by air you definitely need a passport. If by land or sea you can get by with either a cheaper passport card or enhanced drivers license. Regardless the good old days are well behind us now.