Canada Customs:
www.cbsa-asfc.gc.ca/travel-voyage/menu-eng.html

U.S. Customs:
www.cbp.gov

U.S. residents crossing the U.S.-Canadian border either way normally is made without difficulty or delay. Passports are required as of January 23, 2007 when traveling by air. When crossing borders by land or sea, a Passport is not required until January 2008. A Birth Certificate and Drivers License are accepatable forms of identification. Be sure to carry your Vehicle Registration if driving to Alaska
.
Auto insurance is mandatory in all Canadian provinces and in the Yukon territory. Motorists entering Canada may be required to show a Canada Non-Resident Inter-Province Motor Vehicle Liability Insurance Card. This card, which can be obtained from your insurance agent, will certify that the motorist has liability and property damage insurance coverage.

You can bring in personal goods without paying duty or tax, as long as you do not leave them in Canada. You can also bring (minimum 19 years) 1.5 L of wine or 1.14 L of liquor or 24 (12 oz) bottles/cans of beer. 200 cigarettes, 50 cigars and 200 grams manufactured tobacco.

Dogs and cats must be have a rabies vaccination certificate valid within the past 36 months.

Non-residents entering Canada are not permitted to carry revolvers, pistols or fully-automatic weapons under any circumstance. Personal protective sprays such as mace or pepper sprays are not allowed.

If you are a visitor to Canada, you will have to declare your firearms in-writing. Visitors may only import nonrestricted firearms for legitimate purposes such as: sporting or hunting use during hunting season; use in competitions; in-transit movement; personal protection against wildlife in remote areas of Canada, as long as the customs officer is satisfied that the circumstances warrant the firearm being imported.
You can bring in gifts without paying duty or tax, as long as they are not alcohol or tobacco or business goods, and they have a value of CAN $60 or less per gift.
Canadian residents; must include the total value of all goods (including gifts) that you have purchased, received, or acquired abroad or at duty-free shops and that you are bringing into Canada. 24 hours exemption limit $50; 48 hours $200; 7 days $750.