NAFTA

Canadian citizens usually do not need a visa as a NAFTA Professional, although a visa can be issued to qualified TN visa applicants upon request. However, a Canadian residing in another country with a non-Canadian spouse and children would need a visa to enable the spouse and children to be able to apply for a visa to accompany or join the NAFTA Professional, as a TD visa holder. To apply for visa, please see Applying for a TN Visa - Required Documentation.

A Canadian citizen without a TN visa can apply at a U.S. port of entry with all of the following:

Professionals of Canada may work in the U.S. under the following conditions:

• Applicant is a citizen of Canada;
• Profession is on the NAFTA list;
• Position in the U.S. requires a NAFTA professional;
• Canadian applicant is to work in a prearranged full-time or part-time job, for a U.S. employer (see documentation required). Self employment is not permitted;
• Professional Canadian citizen has the qualifications of the profession 

Source: U.S. Department of State

NAFTA is the North American Free Trade Agreement.  It creates special economic and trade relationships for the United States, Canada and Mexico.  The nonimmigrant NAFTA Professional (TN) visa allows citizens of Canada and Mexico, as NAFTA professionals to work in the United States.  Permanent residents, including Canadian permanent residents, are not able to apply to work as a NAFTA professional.

Source: U.S. Department of State 

The following is list of professions which qualify for TN status under NAFTA, and the applicable minimum education requirements and alternative credentials. The U.S. State Department notes:

With some exceptions, each profession requires a baccalaureate degree as an entry-level requirement. If a baccalaureate is required, experience cannot be substituted for that degree. In some professions, alternative criteria to a bachelor's degree is listed. For some professions, experience is required in addition to the degree.