I know it seems like a long time off but starting next June you'll need to present documents proving citizenship and identity when entering the country through a land or sea border.
You can get a passport, but if you drive to Canada or Mexico or regularly head to the Caribbean, you also have another cheaper option that will also allow for a speedier border crossing: a passport card.
Passport cards are the size of a credit card and are imprinted with a photo and ID info. They also also contain a chip that lets border officials instantly retrieve your data, which speeds processing a ton. The cards are good for 10 years and cost $45 ($35 for children under 16); passport books run $100 for adults and $85 for children. If you already have a passport but want the card because of the convenient size or quick scanning, it's only $20 and can be ordered by mail.
The State Department says the cards are proving popular with more than 350,000 Americans having preordered them.
One caveat: The card is not valid for any type of air travel. It can only be used for crossings between into Canada, Mexico, Bermuda, or the Caribbean.
For more info, here's the government site.