Final answer:
The legal environment concerning unionization in the U.S., shaped by the National Labor Relations Act of 1935 and the Taft-Hartley Act of 1947, has fluctuated from supportive to less encouraging, thereby affecting union membership levels.
Step-by-step explanation:
The question addresses the relationship between the legal environment in the United States and the ease with which unions can organize workers and expand their membership. This discussion is grounded in the context of U.S. history and business law, particularly with laws such as the National Labor Relations Act of 1935 and the Taft-Hartley Act of 1947.
Historically, the National Labor Relations Act, also known as the Wagner Act, created a friendly legal environment that allowed for a notable increase in union membership during the 1930s and early 1940s by asserting workers' rights to organize and by obligating management to give them a fair opportunity to do so. The United States government also saw the value in encouraging unionization during World War II to ensure efficient production efforts. However, the passing of the Taft-Hartley Act changed the legal landscape by empowering states to allow workers the option to abstain from joining workplace unions, which contributed to a gradual decline in union membership over subsequent years.
Indeed, U.S. laws have evolved in ways that are relatively less supportive of union formation compared to some other countries, impacting the patterns of job growth and sector representation in unions, as well as overall union membership levels.