I don't agree. Boarding flights to the US from some airports is no big deal, but at others 100% second security inspections are conducted. At a number of Latin American airports travellers to the US aren't even allowed to board with water bottles purchased after the first security screening. I have waited in line almost 90 minutes to clear US immigration at MIA, and I waited 55 minutes at DFW a couple of weeks ago. I have sometimes cleared very quickly, but waits are more common. At most US airports Canadian passport holders are supposed to be able to clear at the US rather than foreign national counters, but not all CBP personnel are aware of this. There's then TSA security to pass before making one's connection, and at some terminals that takes quite a while too. Making an international-international connection at most Canadian airports is a lot less hassle.