From 2009 thru December 2016, the Canadian government did require citizens of Mexico to obtain a tourist visa but that is no longer the case, just a passport and proof of full covid vaccination would be the minimum requirement at the discretion of the CBSA customs officer as far as an individual status goes for permitted entry in Canada upon visiting -
Citizens of other countries may have to obtain a visiting visa as the Canadian government has a listing of who is required to do so, however US and Mexico citizens are two of many countries that do not require a visitors visa to enter Canada ...
As long as the Montana registered vehicle at hand has valid insurance coverage within the United States, most every US insurance carrier will honor the coverage while visiting Canada nowadays without obtaining additional coverage cards, endorsements, etc.
As noted, others had posted
most insurance carriers as it is best to check one's policy of insurance carrier to verify if the policy itself does not clearly state included coverage in Canada...
My insurance carrier did require temporary permit cards for additional coverage in Canada valid for 30 days, at no additional charge when requesting for one as deemed under Canadian law....
The main reason behind it was : Canada coverage requirements were much higher than US carriers (at the time) -
-Alaska liability minimum $100,000 USD
-Alaska property damage minimum $25,000 USD
-Canada liability minimum $200,000 CAD
-Canada property damage minimum $50,000 CAD
My insurance carrier finally stopped issuing the temporary permit cards practice in 2017 as some major US carriers already started to automatically include coverage within Canada anyway, however each carrier still potentially had their own set of rules upon declaring operating said vehicle in Canada or what have you...
I was asked for proof of insurance twice ever while in Canada...
First time was entering Canada at Beaver Creek Yukon in 1991 as the CBSA officer wanted to see proof of insurance as I just obtained an insurance policy and showed it to the customs officer - the officer called out that it didn't show Canadian coverage as I pointed out an endorsement document inside the policy paperwork which stated minimum Canadian coverage limits valid for 30 days as the officer was satisfied...
Second time was in 2013 just 2 km west of the Cassiar Hwy Junction on the Alaska Highway in the Yukon with this unexpected mandatory checkpoint road block courtesy of a joint venture by the RCMP's and the Yukon Wildlife Conservation checking vehicle registrations, valid driver licenses, hunting license-permits, and proof of insurance in both directions :
I submitted my driver license and proof of insurance but could not find my vehicle registration for three minutes as they would not permit me thru until I found it, in which I found the Canadian coverage temporary permit card inside the registration and surrendered it to the officer as she stated "what is this, I never seen any Canadian coverage temporary permit insurance card before".
So as others pointed out reference to permits, visa requirements or additional insurance coverage for Canada, hope the OP is reassured it is not a necessary requirement for permitted entry in Canada...
The CBSA are not the insurance enforcement police as most every time they will not ask for proof of insurance, however they have the power to inquire asking for proof of insurance for compliance check measures at their discretion.
