So this question:
posits what I consider to be an interesting situation. Rochester, NY (USA) is within driving distance of Toronto (Canada), and as Toronto is the much larger city, I would suspect there are many destinations that would make it worth someone's while to use it as a departure point for an international flight.
A transit visa (assuming you needed one) would suffice if you flew from
YVR, and thence onwards - but what if you drove there? Because you didn't stay in the sanitized area, I doubt you would qualify.
Now, in that particular situation (the US & Canada are effectively borderless for their citizens) and others like it (Schengen area, other US-Canada), there is very little cost beyond the gas. But, how does this affect the visa you need at your destination? In other words, what considerations about visas do you need if your flight originates from a country other than the one in which you are a citizen?