You get a bit of the feeling in Toronto and Montreal, but highway infrastructure in the US is just on another level. I can easily see why someone may assume somewhere south of the border is larger than Ottawa based on the number of interstates.
I was in Portland earlier this fall and actually did some driving, which is something that is usually avoided on vacation. Walking around at street level it was clear that Portland isn't a huge city, certainly much less so than I'm used to. Driving on the other hand... It's admittedly partly due to topography, but some of the highway junctions near downtown were just on another level. Driving through you'd think it's a much bigger city than say, Vancouver.
https://goo.gl/maps/cUeB5fi8wXF2
https://goo.gl/maps/gotepbZyxUB2
https://goo.gl/maps/q1wyFL4NvGk