What documents do you need for crossinng US-CA border?

I was thinking of going to Canada with my family for a weekend. We would go there by car. I need some help about the documents needed for crossing the border. We are all US citizens, and I am not sure if we all need passports. Have you recently been there and could you help a bit? Thank you.

Passport is the easiest one, but if you or members of your family dont have it, then you will need to provide any document with a photo ID and any proof of citizenship. For example, a drivers license and birth certificate are enough for grown ups. Children need only one of these: birth certificate, passport, citizenship card or resident card. I hope I help. Have a nice time in Canada!