Union membership is continuing to shrink throughout the country, even as companies add jobs in one-time union strongholds such as Michigan.

Union membership fell to 11.3% of wage and salary workers last year, down from 11.8% the year before, the Bureau of Labor Statistics said today. In 1981, 20.1% of wage and salary workers were unionized.

The latest numbers, while not a surprise, are the result of both political maneuvering and corporate negotiations. Both Michigan and Indiana became right-to-work states over the last year, meaning unions cannot require members to pay dues as a condition of employment. In other states, such as Wisconsin, state governments reduced the power of public employee unions.