Can Canadians register to take the SAT exam in the United States? Yes.
To do so, follow these instructions. The specifics of registration might change, but the main idea is to select the United States as the testing country and to choose a ZIP code just across the border to choose a testing center.
United States 
Finding a U.S. Testing Center
To register for a testing center in the United States, choose “United States, including U.S. territories and Puerto Rico” as the testing Country.
On the next screen, choose a ZIP code of a city near where you want to take the exam. For example, Blaine, Washington, (ZIP code 98230) is just south of the border of British Columbia.
Enter that postal code, then click “Search by ZIP code” and choose a testing center.
