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%. Similarly, Hillary Clinton won the district in 2016 with 54% of the vote over Donald Trump with 38%, and in 2020 Joe Biden polled 59% to 38% for Donald Trump.
The former House seat of powerful U.S. SenatorWarren G. Magnuson, the district was a swing district throughout much of the 1990s, changing hands and parties three times in four elections. Before the election of future U.S. SenatorMaria Cantwell in 1992, the district had been in Republican hands for 40 years (and 42 of the previous 46 years). Since the 1998 election, when Inslee was first elected, the growing Democratic trend in the Seattle area enabled him to turn it into a fairly safe seat. He had been re-elected six times, with little difficulty, most recently in 2010.
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 DemocratSuzan DelBene, defeating RepublicanJohn Koster with a margin that the Seattle Times called "unexpectedly decisive",[6] reflecting the difficulty of predicting the vote in the new district. The certified results confirmed her significant margin.[7] 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.