The state says Washington's population grew by almost 100,000 last year to nearly 7 million.
The Office of Financial Management says the 85,800 increase in 2013 was the largest one-year gain since 2008, bringing the total to 6,968,200.
The office says people migrating into the state accounted for 57 percent of the increase, with births (minus deaths) accounting for the other 43 percent.
It was the first time since the economic downturn that migration exceeded the three-decade historical average.
The office says 75 percent of the population increase went to the five largest metropolitan counties where economic activity attracts migrants: Clark, King, Pierce, Snohomish and Spokane counties.
The top 10 cites for population growth were Seattle, Bothell, Vancouver, Bellevue, Pasco, Redmond, Renton, Auburn, Kennewick and Snohomish.