Or. Const. art. XVI, § 1

State boundaries. The State of Oregon shall be bounded as provided by section 1 of the Act of Congress of February 1859, admitting the State of Oregon into the Union of the United States, until: (1) Such boundaries are modified by appropriate interstate compact or compacts heretofore or hereafter approved by the Congress of the United States; or (2) The Legislative Assembly by law extends the boundaries or jurisdiction of this state an additional distance seaward under authority of a law heretofore or hereafter enacted by the Congress of the United States. [Constitution of 1859; Amendment proposed by S.J.R. 4, 1957, and adopted by the people Nov. 4, 1958; Amendment proposed by H.J.R. 24, 1967, and adopted by the people Nov. 5, 1968]