Northern Mariana Islands Covenant Implementation Act

Northern Mariana Islands Covenant Implementation Act - Declares it is Congress' intention in enacting this legislation to: (1) ensure effective immigration control by extending the Immigration and Nationality Act, as amended, in full to the Commonwealth of the Northern Mariana Islands with special provisions allowing for the orderly phasing-out of the nonresident contract worker program, and the orderly phasing-in of Federal responsibilities over immigration; and (2) minimize, to the greatest extent possible, potential adverse effects such phase-out might have on the economy of the Commonwealth.Amends the Covenant to establish a Commonwealth of the Northern Mariana Islands in Political Union with the United States of America (the Covenant Act) to apply the Immigration and Nationality Act, as amended, to the Commonwealth over a ten-year transition period during which the Attorney General shall implement an immigration transition program for it.Sets forth a statutory scheme for: (1) temporary alien workers; (2) immigrants; (3) adequate employment in Commonwealth's tourism industry after the transition period ends; (4) nonimmigrant investor visas; (5) lawful entry under Commonwealth immigration laws; and (6) entry into the Commonwealth under grandfather provisions for certain long-term employees.Directs the Secretaries of the Interior and of Labor to develop a technical assistance program to aid Commonwealth employers in securing employees from among U.S. labor, including lawfully admissible freely associated state citizen labor.Prohibits the Commonwealth from permitting an increase in the total number of alien workers present there on the date of enactment of this Act.