USA, CANADA border
 

Next September my family and I will be in Bellingham Washington, we are hoping to drive to Vancouver, British Colombia, Canada and back, for 5 consecutive days.
Is there a problem we will encounter at the border?
We have a valid USA visa as well as a valid Canadian visa.
Please advise.

Assuming your visas are in order and allow repeat entries into both countries, you shouldn't have any particular difficulties apart from traffic delays at the border. Note there are two highway crossings, the "Peace Arch" at the Interstate 5 - BC 99 crossing, and the "truck crossing" aka "Pacific Highway" crossing a couple of km east. There are signs indicating the current crossing time delays along I-5 and BC 99 as you approach the border. https://goo.gl/maps/YR1mzroYSvkoHNtn8

B1 or B2 visa? (USA)

In general this is always the case: " It really depends on the specific circumstances and discretion of the CBP officers who review your case each time you enter."

Canadian visa types:

• Visitor visas.
• Student visas.
• Work visas.
• Permanent Residence visas.
• Business Immigrant visas.
• Express Entry Program visas.

Which one do you have?

In all cases it is always at the discretion of the officer what problems you might encounter.

We have multiple entry visas for both countries. But we are still afraid they will ask about the reasons of multiple entry in a short period of time, only a couple of days.

OTOH, admitting openly you're a mule won't fly either.... IF that's the case....

The vehicle you drive might also make a difference.... I don't recommend a Cheech & Chong van
Attachment 8169

USA, CANADA border
 

I am sorry to hear that, and I appreciate your help.
OTOH, admitting openly you're a mule won't fly either.... IF that's the case....

The vehicle you drive might also make a difference.... I don't recommend a Cheech & Chong van
Attachment 8169[/quote]

The #516 Amtrak Cascades northbound train leaves the Amtrak station in Bellingham (401 Harris) shortly before 10 AM daily and is in Vancouver BC about noon. If you arrive in Canada on the train you don't have the problems with a rental car across the border (insurance etc.). You also won't have the hassle of paying for parking etc.
My short trip into Canada last month was north of Metaline Falls WA toward Salmo BC. I had no stop on the US side of the border. The Canadians asked their questions after inspecting my US passport. They said "pull into the second bay" and come back in here. After 22 minutes they came back and said I was good to go. When I came back into the US, I had a couple of questions to answer but was let back into the US in about 2 minutes.

Thanks for your advice. We will definitely think about it.