The Washington State Boundaries Amendment, also known as Senate Joint Resolution 10, was on the November 4, 1958 ballot in Washington as a legislatively-referred constitutional amendment, where it was approved. The measure authorized the modification of state boundaries along the Columbia River. The measure amended Section 1 of Article XXIV of the Washington Constitution.
| Washington SJR 10 (1958)|
| Yes|| 395,969|| 56.09%|
Election results via: Washington Secretary of State
Text of measure
- See also: Washington State Constitution, Section 1 of Article XXIV
The language appeared on the ballot as:
|| STATE BOUNDARIES: MODIFICATION BY COMPACT
Shall Article XXIV, Section 1 of the state constitution be amended to authorize the modification of the boundaries of the state of Washington by appropriate interstate compacts duly approved by the Congress of the United States?
When Washington became a state in 1889, the law defined the center of the Columbia River as the boundary between the state and Oregon. Due to natural and human factors, the river's center changed. This resulted in problems of tax assessments, liability insurance claims and fishing rights.