Lost jobs, right to work laws, a weak economy, all are reasons why. The Unions however fail to recognize that perhaps they're part of the reason why the jobs are being lost:
Hostess closed down because of the unions, resulting in a multitude of lost jobs, and, as the article notes, most job growth has taken place in nonunion firms.But unions also saw losses in the private sector, even as the economy expanded modestly. That rate fell of membership fell from 6.9 percent to 6.6 percent, a troubling sign for the future of organized labor, as job growth has generally taken place at nonunion firms......"Our still-struggling economy, weak laws and political as well as ideological assaults have taken a toll on union membership, and in the process have also imperiled economic security and good, middle class jobs," said AFL-CIO President Richard Trumka.
This might not be the death knell of unions, but its obvious that the union movement isn't completely healthy either.