Not Panama - the
Canal Zone.
After all - there haven't been any Isle-wide referenda in Eire supporting British Union either
But a Canal Zone referenda, back when the zone was under US control, would've been overwhelmingly positive. - as the Zone was primarily 'populated' by US military.
But the real question is - what would be the point of keeping the zone - from a practical sense as opposed to generic jingoism - for the US?
Anyone running the canal is going to be operating in the US interest in a practical sense, so there isn't a need to 'protect' it, absent a world war scenario.
Heck if we weren't going to annex Panama (unlikely, given our issues with latino culture, especially back then), then what is the point of demanding sovreignty over a strip a few miles wide right through the middle of the country? It's on par with demanding sovreignty over arab oil wells - what is the point? They have to sell the oil - there's nothing else going for them. Even Ayatollah Rock-n-Rolla Kook-zanny himself noted that the oil was only good for selling - his people couldn't drink the stuff.