One route, followed properly: Porto (OPO) to Miami (MIA), return. What follows is the lowest fare our radar has picked up on it and the precise dates behind that number, rather than a headline price with the conditions left out.
We do not post a price and leave it to age. Each fare is re-checked against Skyscanner on a schedule and carries the time it was last confirmed. Not flying from Porto? We track 58 other departure cities for Miami, listed at the foot of this page.
Cheap fares do not hang around. If this one has already gone, nudge the dates either way by a day or two; Porto to Miami is usually still decent value around the same window.