Does United States require proof of onward travel?

What to have ready

An onward flight is the safe answer — dated inside your permitted stay, with a booking reference the airline can verify · official source ↗ · entry requirements (Gov. of Canada) ↗. Airlines carry the fines when a passenger is refused entry, so the strictest check usually happens at check-in, before you board.

Travelling one-way? Three legitimate fixes, safest first

1. A refundable real ticket — book a fully refundable fare out of United States and cancel it once you're through. Bulletproof; the only cost is having the fare tied up for a few days.
2. A cheap genuine exit flight — a budget one-way to a nearby country is often US$20–50 and is real proof by definition (you can even use it).
3. A rented onward reservation — a real, short-lived airline booking with a checkable PNR. Usually fine at airline check-in; riskier with strict immigration officers, who may re-check the PNR on arrival (an expired one can cause problems), and never appropriate for a visa application.

Whichever you choose, it must be a real booking — an edited PDF or an invented reference is document fraud, and officers can type the code into their system.