Canoeing laws vary from state to state. A Pennsylvania resident once told me a permit was required to paddle on rivers in his state (seriously!?). In Texas, life jackets are required for kids 13 and under when paddeling recreational canoes, and anyone over 13 must at least have one in the boat. In Connecticut paddelers of all ages are required to wear life jackets while paddling during the cold months of the year. And yes, I have been stopped by a game warden before who was all too happy to write tickets.
The US Coast Guard website is (obviously) a great place to look. Not only do they have federal laws, they also have a great tool for finding boating laws for your state.
Personal Note
Frankly, I don’t love the government telling me how I can or can’t canoe of all things. That being said, these types of laws were almost always created because people died. So, don’t just avoid getting a fine, use your common sense out there, and take safety seriously.