The minimum wage in Washington state will increase to $9.47 an hour beginning Jan. 1, up 15 cents from the current hourly rate, the Washington state Department of Labor and Industries announced today.

The change reflects a 1.59 percent increase in the federal Consumer Price Index for urban wage earners and clerical workers during the 12-month period ended Aug. 31. As required under Initiative 688, which voters statewide approved in 1998, the state’s minimum wage is tied to that index.

L&I said in a press release that the per-hour increase will total $312 a year and will affect more than 67,000 workers statewide.

The minimum wage applies to all industries, including agriculture, although 14- and 15-year-olds can be paid 85 percent of the adult minimum wage, or $8.05 an hour.

Washington state currently has the highest minimum wage in the U.S., continuing to outpace Oregon, which will raise its minimum wage 15 cents to $9.25 in 2015, L&I said.