As its share of ballots cast by mail has steadily increased, Washington state in 2010 reached a new high in national ranking of “voting-eligible population” voter turnout, a more precise measure of civic engagement than the traditional turnout reports on the percent of registered voters who voted. One of only two U.S. states along with Oregon where all voting is now by mail, Washington state ranked second highest in percent of the voting-eligible population which actually cast ballots counted in the November 2010 elections. This is according to a recently updated report based on government data and released by the United States Elections Project at George Mason University.

Although most media reports traditionally frame voter turnout simply in terms of the percentage of registered voters who vote, that measure ignores a sizable group of citizens who are eligible to vote but fail to even register. The “voting-eligible population” in each state is determined by the United States Elections Project by using data from the U.S. Census and the Census Bureau’s American Community Survey, as well as the U.S. Department of Justice. Along with those too young to vote, non-citizens and ineligible-to-vote felons are filtered out, to arrive at voting-eligible population.

In Washington state in the 2010 mid-term elections for Congress, state, regional, and local offices and ballot measures, 54.3 percent of voters who were actually eligible to vote turned in counted ballots. Only Minnesota had a higher rate, 55.9 percent. Tied for third were Oregon and South Dakota at 53.9 percent.

By 2010, according to data from the Washington Secretary of State's office, 98.7 of Washington votes were classified as "absentee," sent in by mail. By the fall 2011 elections, 100 percent of votes were cast by mail in Washington. Another factor likely to have influenced turnout in Washington in 2010 was the presence of several hot-button ballot initiatives on the fall ballot. Voters decided measures on a new state income tax for high earners, liquor privatization, a two-thirds legislative majority requirement for tax hikes, and proposed state withdrawal from worker’s compensation. In addition, there was a U.S. Senate contest between incumbent Patty Murray and challenger Dino Rossi.

Nonetheless in the previous mid-term election of 2006, Washington voters also faced controversial ballot initiatives and another U.S. Senate contest, but the percent of ballots cast by mail statewide was 10 points lower than in 2010 and the state’s rank in percent of voting-eligible population whose ballots were counted was not 2nd nationally as in 2010 but 17th, at 47.3. In the 2002 mid-term, only 65.7 percent of Washington ballots were cast by mail and the state ranked 19th in percent of voting-eligible population whose ballots were counted.

David Ammons, a spokesman for Washington Secretary of State Sam Reed, said that although outreach by public officials, campaign spending on ads, and ballot measures all influence turnout, it’s still “hard to overstate the influence of vote-by-mail” on voter participation. “Having the ballot in your house for three weeks is a powerful reminder” to complete it and send it in by election day, and it’s a lot easier than trying to find time to make your way to a physical polling place on election day, he added.

Michael McDonald, an associate professor at George Mason University in Fairfax, Virginia, is the founder and director of the United States Election Project. He said vote-by-mail rates can and do influence off-year elections but are not much of a factor in presidential year elections when more voters are determined to vote whatever the circumstances. “It makes some sense” that the increasing vote-by-mail rate in Washington state is related to the high turnout of eligible voters in 2010 but several more years of off-year election data are needed to confirm the connection, he said.

Nationally, in the 2010 mid-term elections 41.7 percent of the voting-eligible population turned in counted ballots. The traditionally-calculated voter turnout figure was higher. According to the U.S. Election Assistance Commission’s 2010 Election Administration and Voting Survey, 48.6 percent of registered voters voted.

This story is originally appeared on Public Data Ferret and is reprinted with permission. Public Data Ferret is a project of the non-profit Public Eye Northwest.