The Trans-Canada highway north of Lake Superior is the main E-W road and is busy during the summer. If a trip is planned to avoid the summer holidays when kids are out of school and families are travelling, the traffic is minimal. July and Aug are high volume. I rode out to Ontario and back a couple of summers ago during the last 2 weeks of June and except for big trucks, the road was nearly empty away from the few cities. No motorhomes or camping trailers, no strings of traffic and the provincial campgrounds were open but nearly deserted. The first couple of weeks of Sept would be the same. Carry your warmest gear and watch out for moose.