It stretches from Bellingham and the Canada–US border in the north down to the Skagit/Snohomish county line, with a narrow strip along the coast running down to Lynnwood and the King/Snohomish county line in the south.

It was a reliably Democratic district for most of the latter half of the 20th century, until the Republican Revolution of 1994, when retiring Rep. Al Swift was replaced by Jack Metcalf.

In the 2008 election, Larsen easily defeated Republican challenger Rick Bart.

In the 2010 election, Larsen narrowly avoided defeat against Republican challenger John Koster.

Under current boundaries, Barack Obama swept the district in 2008 and 2012, with 58% of the vote each time.