Northwest Territory of the Great Lakes National Heritage Area Act of 1999

Northwest Territory of the Great Lakes National Heritage Area Act of 1999 - Establishes the Northwest Territory of the Great Lakes National Heritage Area, composed of specified historically significant areas, as defined by the Northwest Territory of the Great Lakes National Heritage Area Authority, within Illinois, Indiana, Michigan, and Ohio.

Declares the Authority the Area's management entity, which shall: (1) develop a management plan; (2) help ensure the conservation, interpretation, and development of the historical, cultural, natural, and recreational resources related to the Northwest Territory of the Great Lakes during the period from 1785 through 1835; and (3) develop an Internet web site and other marketing programs, as well as visitor centers and interpretive facilities.

Subjects the plan to approval by the Governors of the States involved.

Authorizes appropriations, with a maximum 50 percent Federal match for the total cost of any assistance or grant provided or authorized.