Iirc, it is a state decision. It is hard to get firm answers as there are different concepts that overlap:
Is it legal to pay someone to vote a certain way? Saying 'no' does not mean it is a truly secret ballot, but it is something.
Is the ballot printed by the govt as opposed to parties or organizations? (Meaning there is an "official ballot" and not just any piece of paper) At one point this was a new thing.
Are you doing an oral vote?
As it is, I think in general you end up with no obligation to share your vote, but that is not the same as any legal obligation to make the voting booth well concealed, depending on state, but that is no small amount of reading between the lines and conjecture on my part, so dont trust me too much.
Is it legal to pay someone to vote a certain way? Saying 'no' does not mean it is a truly secret ballot, but it is something.
Is the ballot printed by the govt as opposed to parties or organizations? (Meaning there is an "official ballot" and not just any piece of paper) At one point this was a new thing.
Are you doing an oral vote?
As it is, I think in general you end up with no obligation to share your vote, but that is not the same as any legal obligation to make the voting booth well concealed, depending on state, but that is no small amount of reading between the lines and conjecture on my part, so dont trust me too much.