Union membership in Ohio fell again last year, bucking a national trend and marking at least the 10th consecutive year of declines for organized labor in the state, according to federal labor data.

In addition to fewer residents being members of unions, union membership continues to account for a dwindling portion of the state’s overall work force.

Some conservative groups said the economy is changing and unions are disappearing because they are “outdated.” But union supporters said the declines simply show that employers are choosing to outsource high-paying jobs to cut labor costs and maximize profits.

“The vast majority of those union jobs have left the state in Ohio have gone overseas,” said James Winship, president of the International Union of Electronic Workers-Communication Workers of America Local 755 in Dayton.

Union membership also makes up a shrinking portion of Ohio’s work force. Union members accounted for 13.4 percent of the state’s work force in 2011, down from 13.7 percent in 2010 and 14.2 percent in 2009. A decade ago, 17.6 percent of Ohio workers were in unions.

Union membership increased in 2011 nationally after three years of declines.

Caroline Merithew, an associate professor of history with the University of Dayton, said the decrease shows that political attacks on organized labor have paid off and reflects an erosion of high-paying manufacturing jobs.

“(The term) Union jobs is to me code for good-paying jobs with benefits that can sustain a family,” she said, adding that creating low-wage jobs in Ohio will not foster a strong economic recovery.

Kevin Holtsberry, president of the Buckeye Institute for Public Policy Solutions, said the decrease in union membership shows the modern economy requires higher skill sets and education levels, and unions provide “an outmoded, inflexible system” that arose during a completely different work landscape.