Most Helpful Guy
Visit the TSA website. There will be a list of things you can't take in your luggage. There's a difference between carry-on luggage and checked luggage. When in doubt, put it in the checked bag. You can have a gun, ammunition in a checked bag. NOT a carry-on. Just to give you an idea about your little knife.
A knife is something you should put in your checked bag. They let you take hatchets, swords, all that stuff ... in the checked bag.