Can I visit Vancouver, Canada and return to the US on the same day?
Sure you could - technically. Depending upon where in the U.S. your adventure begins, you could arrive in the early morning and fly out late at night. But why would you want to do that? It's a gorgeous city, in a gorgeous setting, with lots to see, do - and eat. You'd be spending a fair number of bucks and not getting much bang for it. Airbnb is big there, so it wouldn't cost you very much at all (especially in relation to the cost of your flight) to stay an extra day or two. Check this out for some ideas of why Vancouver might be worth more than an 18-hour-or-so visit: Top 10 Things to Do in Vancouver