Is it legal for me to have sex with a 16 year old girl if we are both willing to?

If you both live in Minnesota, have sex in Minnesota, and you have no position of power or authority with respect to her, such as a teacher, coach, minister, step-father, guardian, doctor, therapist, person of trust, etc., and it is all consensual, then it is probably legal, if not a little creepy.  On the other hand, if she changes her mind later and decides you coerced her, etc., it might not be such a good idea.