What elements of American constitutionalism have proved most influential? Least influential? Why?

and

Why has federalism, an American invention, proved especially popular in other countries?

We don't DO students' assignments, but we'll be glad to comment on your answers.

Alright, well I was thinking that the fact that America's government is run by the people is most influential. However, I can't seem to find an idea that is least influential. Could you be able to guide me towards the right idea?

Probably least influential is our separation of church and state.

Do you think that the people's government is one of the most influential ideas? That or having 3 branches in the government + checks and balances?

Both are very important.