LYNN ? Labor union membership in Massachusetts declined by 35,000 in 2007, according to a new report by the U.S. Department of Labor’s Bureau of Labor Statistics.Current union membership has leveled off at 379,000 statewide. The loss of membership was in stark contrast to the national labor market, where the number of workers belonging to a union increased last year by 311,000 to nearly 15.7 million.Among the highlights in the report: Union members accounted for 13.2 percent of wage and salary workers in Massachusetts, down from 14.5 percent in 2006. Nationally, union members accounted for 12.1 percent of employed wage and salary workers, essentially unchanged from 12 percent in 2006.The report also noted that Massachusetts was one of 20 states that had union membership rates above the U.S. average in 2007.Joining Massachusetts with higher rates were Connecticut with 15.6 percent and Rhode Island with 15 percent. The remaining three New England states posted rates below the national average ? Maine with 11.7 percent, Vermont at 10.4 percent, and New Hampshire a 9.7 percent.Walter Marshall, a regional economist at the Bureau of Labor Statistics, said the decline of union membership in Massachusetts is driving by the loss of manufacturing and the decreased bargaining power of unions in general.”We’ve seen a decline in manufacturing, which is normally heavily unionized. And in general, the unions have lost some of their bargaining power over the past 20 years,” he said. “So it’s a combination of the two.”Marshall said the Northeast traditionally has a strong acceptance of unions. “Unions have been culturally part of the workplace in New England and New York, compared to places like Texas. And if you look at the Midwest, you’ll tend to see unions more accepted in businesses like auto suppliers, but not all businesses.”Jeffrey Crosby, president of the North Shore Labor Council and IUE-CWA Local 201, said many Massachusetts want to join unions but fear reprisal. “Lately I’ve seen increased interest in unions. I had three calls this week, all unsolicited, from people who want to organize,” he said. “But the first question people ask is, ‘Will I get fired?’ Or they ask whether the owners will close the facility if the workers unionize.”Crosby said the laws protecting workers in such circumstances are not strong enough in Massachusetts. “There is a huge gap between people’s interest in joining unions and their ability to do so,” he said. “That’s why we’re trying to change the laws in the private sector. But the biggest issue we face is fear of retaliation, and you only have to look at Enterprise car rental for that.”Crosby noted that Enterprise drivers and fleet preparation workers last year tried to organize, only to see the company outsource the entire operation to a private vendor. “That’s what Enterprise did, and the National Labor Relations Board said it was just fine,” he said. “That’s insane. The public sector is easier, but the private sector is brutal.”The report on union membership was compiled with data from the Current Population Survey, a monthly Census-based household survey which provides basic information on the labor force, employment, and unemployment.Although the state’s 2007 union membership level was the lowest recorded in the 19 years of the data series, Massachusetts still ranked in the top quarter or 12th among all state levels nationwide. At the peak in 1990, union membership in Massachusetts was 17.5 percent, or 479,000 workers. In 1983, the first year for which comparable national union data was available, the union membership rate was 20.1 percent.