Thank you for providing us with an opportunity to teach our readers a short lesson in rhetoric! Your question is an example of a loaded question, a question which contains controversial assumptions and that limits direct replies to those that serve the questioner’s agenda. The most famous example is:
“Have you stopped beating your wife?”
To answer either “yes” or “no” is to implicitly admit that I did beat my wife at some point in the past, which is an assumption that (in my case) is thoroughly false.
So, we first need to address your hidden assumption: Do Mormons think Jesus was American?
No. We believe He was born in Bethlehem, grew up in Nazareth, and limited most of his traveling during his mortal life to the region of Palestine (he made a brief trip to Egypt when he was very young). He was thoroughly Jewish in ethnicity, culture, and nationality.
Mormons do believe that following his crucifixion (Matthew 27), resurrection (John 20), and ascension (Acts 1) in Jerusalem, Jesus visited the peoples living in the Americas (Book of Mormon, 3 Nephi 11). He descended from heaven, lighted upon their temple and said,
Arise and come forth unto me, that ye may thrust your hands into my side, and also that ye may feel the prints of the nails in my hands and in my feet, that ye may know that I am the God of Israel, and the God of the whole earth, and have been slain for the sins of the world.
Jesus did visit the American people because he died for them as much as for Peter or Mary. He loved them all, despite nationality. You can read about his teachings and miracles among them in the Book of Mormon, 3 Nephi chapters 9 through 28.
He loves you, too. He will visit you through the Holy Ghost and he will show you that he is the God of the whole earth. He has been slain for your sins. Search diligently for His hand in your life and you will find it.