+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
This was before covid. You need to read the big yellow box for the changes due to covid.

https://www.canada.ca/en/immigratio.../permit/temporary/eligibility.html#port_entry
Yeah, the big yellow box includes these relatively simple to understand words:

You can only apply at the port of entry if you meet all of these conditions:
  • you’re entering Canada from the United States
    • you cannot travel from inside Canada to the port of entry (in other words, you cannot “flagpole”)
  • [...]
 
Guess comes down to interpretation of travelled to the USA if that implies actually entering the US formally and returning as opposed to a flagpole admin refusal.
The bigger trouble will be how will one travel to USA. Border is closed on both sides.
 
One can fly to the US no issues.
But what will be one's reason to visit USA when US immigration asks that. Why are you here? Will we say just visiting? In the middle of pandemic? Or going to Canadian border? Won't it sound fishy?

Mind you, you will have to fly somewhere near to border. Like Seattle.
 
There are no restrictions on entering the US from Canada by air. You can answer however you want, but there are no restrictions to enter US by air from Canada.
 
I work in IT and have a WP approval letter for my ICT Visa. My employer can provide a letter saying my job offer is still valid and i am required to be in Canada. Can anyone please let me know if they have seen/heard of cases like these being allowed into Canada recently? I have also applied for PR and hope if I am refused admission, it should not impact my PR adversely.
I am in USA

Thanks
.