23 United States Code – Section 140
(d) Indian Employment and Contracting - Consistent with section 703(i) of the Civil Rights Act of 1964 (42 U.S.C. 2000e-2(i), nothing in this section shall preclude the preferential employment of Indians living on or near a reservation on projects and contracts on Indian reservation roads.
States may implement a preference for employment of Indians on projects carried out under this title near Indian reservations. The Secretary shall cooperate with Indian tribal governments and the States to implement this subsection.
Executive Order 39 - Affirmation of the government-to-government relationship between the State of Wisconsin and Indian Tribal Governments located within the state of Wisconsin (2004).