The state Office of the Insurance Commissioner counted 970,000 uninsured Washington residents last year. That number is now 600,000 or about 8.65 percent of the state population.
Agency spokeswoman Stephanie Marquis told The Olympian two factors are driving the improvement: enrollment in Medicaid and sign-ups for private insurance, both inside and outside of the new state health insurance exchange.
The insurance department reports the individual market has grown to more than 327,000 policies. That represents about 81,000 more insured people than before Oct. 1, when Washington's Health Benefit Exchange opened.
About half of the people who have bought new individual insurance policies have done so through the exchange; the other half has purchased insurance through a broker or agent outside the exchange.
The exchange also helped sign up nearly 350,000 people for free insurance through Medicaid, since Washington state expanded eligibility for the federal and state program. But many of the new Medicaid enrollees were eligible before the expansion and may not have known about their eligibility.
Beth Luce, spokeswoman for the Health Care Authority, said data through July 10 showed an additional 190,865 people have been signed up for Medicaid who were already eligible under tighter standards in effect before the Affordable Care Act took effect.
The decrease in uninsured Washington residents mirrors the enrollment trend in the more than two-dozen other states that expanded Medicaid eligibility.
The national rate of uninsured has also dropped. A report last week from the Commonwealth Fund said 15 percent of Americans are uninsured, compared to 20 percent in the third quarter of 2013.