Oh Canada, New Entry Requirements!
What it takes cross the border by land or by sea

New entry requirements take effect January 31, 2008
Entry requirements for land and sea travel between the U.S. and Canada will change on January 31, 2008. The hop and skip across the border will include more of a jump (through hoops) in the form of added documentation. Two forms of ID will be required: government-issued photo ID and a document showing the holder's U.S. citizenship. In this day of heighten security, it's hard to believe that a verbal declaration of citizenship was once all you needed to visit our neighbors to the north.
Entry requirements for traveling to Canada
Beginning January 31, 2008, travelers entering the U.S. from Canada by sea and land must have government-issued photo identification and a document showing their U.S. citizenship (for example, an original or certified birth certificate or certificate of nationalization).
Americans traveling between the U.S. and Canada by air must have a valid passport. (This rule has been in place since last year.)
A Trip Tip for Frequent Cross-Border Drivers
If you drive frequently between the U.S. and Canada, consider the NEXUS program. It's designed to expedite border crossings for pre-screened and approved low-risk travelers.
Introducing the U.S. Passport Card
Beginning in spring 2008, the passport card will facilitate entry and expedite document processing at U.S. land and sea ports of entry when arriving from Canada, Mexico, the Caribbean and Bermuda. Be clear that this is not a passport but a new form of ID introduced as a less costly option for U.S. travelers visiting the aforementioned destinations.
Related Links:
Canadians: Travel Documents for Entering the United States
Got the border-crossing blues? Here's what you need to know.