Hi alan,
Originally Posted by
alanR
As a US citizen you have an absolute right to be in the US, so as long as you can prove you are an American citizen then you don't need to present a non-US passport.
Isn't it actually illegal for a US citizen to enter the US on another country's passport?
I also wouldn't present the UK passport by itself when leaving the US as otherwise the lack of an entry stamp may raise a few eyebrows
And the airline will want proof of your legal visit to the US, typically through the stub of your I-94. Not having that will raise all kinds of questions.
Cheers,
GenevaFlyer