Updated June 26, 2014
Changes to the requirements for border crossing between the United States and Canada have long been rumored and several times delayed. As of January 31st, however, the new rules took effect. During this transition period, crossing the Canadian border by land requires a passport or a driver's license and birth certificate. The requirements will ratchet up a notch in June of 2009, when a passport becomes mandatory. Note: During the transitional/educational phase, crossing guards have some latitude. If you don't have the required documentation, you may still be allowed to cross over the border. You will, however, be given an informational flier.
Detroit-Windsor Crossing Options
There are several options for crossing into Canada from the Metro Detroit area. From Detroit proper, there are two options within a couple miles of the other: The Ambassador Bridge, which is privately owned, and The Detroit-Canada Tunnel, both of which connect Detroit to its neighbor to the south, Windsor, Ontario.
Port Huron/Sarnia Crossing
An alternative to the Windsor crossing is Port Huron, north of Detroit via I-94, to Sarnia, Ontario on the Blue Water Bridge.
When choosing which to use, the Canada Border Services Agency
provides real-time, border-crossing wait times.