What are the requirements for infants in the US to travel to Canada?

They have to be able to recite the Pledge of Allegiance. And they can't travel by themselves. Seriously, there are no requirements, but you should carry proof of citizenship just so you have no problems bringing an infant back INTO the States.

Well I found this website with some info..seems like if you apply for this pass it makes it much easier to get into canada
http://www.cic.gc.ca/english/visit/travellers.html#nexus

here's another website
http://www.explore.canada.travel/ctc/ke/things_to_know_2.jsp?cat=4004&localeId=16

I am assuming if you have your child's birth certificate and your ID you'd be good to go...

I use to work for an airline. the biggest thing you would need is a birthcert. if the parent is traveling alone then do yourself a favor and get a letter from the other parent saying they have permission for the child to leave the country. otherwise they can be called on kidnapping.

Current Requirements for Entry Into Canada

Visas are not required for U.S. citizens entering Canada from the U.S. You will, however, need:

1.
Proof of your U.S. citizenship such as your U.S. passport or certified copy of your birth certificate issued by the city, county or state in the U.S. where you were born. If you are a naturalized U.S. citizen and do not have a passport, you should travel with your naturalization certificate. A driver’s license, voter’s registration card or Social Security card is NOT valid proof of citizenship.
2.
Photo identification, such as a current, valid driver’s license.




Due to international concern over child abduction, single parents, grandparents, or guardians traveling with children often need proof of custody or notarized letters from the other parent authorizing travel. (This is in addition to proof of citizenship as explained above.) Any person under the age of 18 and traveling alone should carry a letter from his/her parent or guardian authorizing the trip. Travelers without such documentation may experience delays at the port of entry.