https://help.cbp.gov/app/answers/detail/a_id/751/~/traveling-to-other-countries-while-in-the-u.s.-on-a-b1-or-b2-visa
B-1 or B-2 visas: During your visit to the U.S., you may visit Canada or Mexico for up to 30 days and re-enter the U.S. as long as you re-enter within the period noted on the Form I - 94 which you received when you first entered.
I am not sure if they mean by American Perspective ( typically once you are in US, you can stay upto six months ) , you still might need a visa fro Canada ( 90% sure ) if f understand it correctly