Paperwork needed.
We advise you get passports. You do not need a passport to enter Canada unless you are flying in. (You need a passport to get on a plane in the US.)
However, the US Homeland Security is tough on Americans returning without passports and have a bad habit of detaining US citizens and visitors alike if they do not have passports.
For the marriage licence you need 2 pieces of photo ID, such as a state birth certificate, passport, valid drivers licence.
