An Act Providing that at two o'clock antemeridian Pacific Standard Time of the last Sunday in April each year the time of the State of Washington shall be advanced one hour, and at two o'clock antemeridian Pacific Standard Time of the last Sunday in September in each year the time of the State of Washington shall, by the retarding of one hour, be returned to Pacific Standard Time.
Source for Popular Vote data: Washington Secretary of State. November 1960 General, Washington Secretary of State (http://www.sos.wa.gov/elections) (accessed 15 Oct 2013)