What impact did european contact have on native american population between 1500 and 1620?

It decreased and very significantly so!

Most of native Americas died of diseases brought by Europeans; but some were also killed directly by the Europeans. Many also mixed with the Europeans (by marriage or rape...) so there was also a mixed indigenous-white population.

Protecting and assisting  u.s. citizens  living or traveling abroad; assisting u.s.  businesses  in the international marketplace; coordinating and providing support for international activities of other u.s. agencies (local, state, or federal government), official visits overseas and at home, and other diplomatic efforts.keeping the public informed about u.s. foreign policy and relations with other countries and providing feedback from the public to administration officials.providing  automobile registration  for non-diplomatic staff vehicles and the vehicles of diplomats of foreign countries having  diplomatic immunity  in the united states