The 2018 Washington State Senate elections took place as part of the biennial United States elections. Washington state voters elected state senators in 25 of the state's 49 Senate districts. The other 24 state senators were not up for re-election until the next biennial election in 2020. State senators serve four-year terms in the Washington State Senate. A statewide map of Washington's state legislative districts is provided by the Washington State Legislature here, Archived 2018-10-24 at the Wayback Machine.
A top two primary election on August 7, 2018, determined which candidates appear on the November 6 general election ballot. Each candidate is allowed to write in their party preference so that it appears as they desire on the ballot.[1]
Democrats expanded their caucus's majority to 28–21 by further flipping the 26th, 30th, and 47th districts. Tim Sheldon was reelected as a Democrat, but continued to caucus with the Republicans.
^ abcdefOne Democrat, Tim Sheldon, caucuses with the Republicans, which gave them majority control from 2013 to November 2017, and is counted in the Republican seats