What do the countries of canada, the united states, and mexico have in common?

Geographically, Canada, the United States, and Mexico are found in North America. 

These countries also formed NAFTA. NAFTA stands for North American Free Trade Agreement. It established a free-trade zone in North America and was put in force on January 1994. 

Under NAFTA:
1) All co-signers are equal. Each must treat other co-signers as equal w/o favoring another to the detriment of the other.
2) Tariffs on imports and exports of the 3 signatories are eliminated
3) Exporters must have a Certificate of Origin to have their tariffs waived. This means that exported products must only be from Canada, the United States, or Mexico.
4) Trade disputes are resolved under NAFTA's established procedures
5) Copyrights, Patents, and Trademarks are respected.
6) Business travelers have easy access in these 3 countries.