I have crossed the border many times....
if you are a US citizen, goingto into canada is almost laughable. You
will likely just get a few qwuestion, where, purpose, how long of your
trip, maybe a "whose got the child?", if you are traveling with a car
seat, but no occupant......
the questioning is very standard, but a curve ball is sometimes tossed
and your answer to that one will determine how much of a hassel any
form of ID will be. A birth certificate(make sure it has a raised
seal) and a liscense are perfectly acceptable, and you will move
through very quickly into canada....
coming back to the states, it is much the same, but they will look a
lot more closely at your documents, so have them ready, and expect a
heavier look or 2 if you dont have a notarized copy of the birth
certificate. I wouldnt think you will have any problems at all.
Chuck