Washington's 1st Congressional District

Washington's 1st congressional district encompasses the majority of Whatcom, Skagit, and Snohomish counties, as well as nearly one-third of King County. The eastern edge of the district follows county lines from the Canadian border down to the I-90 corridor. Then it follows I-90 west to West Lake Sammamish, and from there north to I-5. The western border follows the I-5 corridor north to Bellingham, then along the coast to Canada.

The 2012 redistricting drastically changed the 1st district. Much of this area was previously part of the 2nd district, but in the new map the 2nd has shrunk significantly. Jay Inslee (D) was the representative of the 1st District until resigning to run for Governor of the state, but most of the district has been represented by Rick Larsen (D), of the 2nd District, in the past.

Soon after the 2012 general election polls closed, the Seattle Times and national news organizations called the district for Democrat Suzan DelBene, defeating Republican John Koster with a margin that the Seattle Times called "unexpectedly decisive", reflecting the difficulty of predicting the vote in the new district. The certified results confirmed her significant margin. DelBene also won the election for the remainder of Inslee's term in the old First District, and after being sworn in on November 13, 2012, is serving in the 112th Congress.

In presidential elections, the 1st District has leaned Democratic. Under the old boundaries, Al Gore and John Kerry narrowly carried the district in 2000 and 2004 with 48% and 51% of the vote, respectively. In 2008, Barack Obama swept the district with 55.60% of the vote while John McCain received 42%.