1. Articles of Confederation: Privileges and Immunities Clause

Article IV, Clause 1.

The better to secure and perpetuate mutual friendship and intercourse among the people of the different States in this union, the free inhabitants of each of these States, paupers, vagabonds, and fugitives from justice excepted, shall be entitled to all privileges and immunities of free citizens in the several States; and the people of each State shall have free ingress and regress to and from any other State, and shall enjoy therein all the privileges of trade and commerce, subject to the same duties, impositions, and restrictions as the inhabitants thereof respectively, provided that such restrictions shall not extend so far as to prevent the removal of property imported into any State, to any other State, of which the owner is an inhabitant; provided also that no imposition, duties or restriction shall be laid by any State, on the property of the united States, or either of them.

2. U.S. Constitution: Privileges and Immunities Clause of Article IV, Section 2

The citizens of each State shall be entitled to all the privileges and immunities of citizens of the several States.