Final answer:
Union density reflects the percentage of workers in a labor market or company who are union members and is a true measure of a union's relative strength or potential influence. The U.S. has experienced a significant decline in union membership since the 1950s, with several contributing factors and differences when compared to other high-income countries.
Step-by-step explanation:
The statement that 'union density, the proportion of a total group comprised of union members, is one measure of relative union strength or potential influence' is true. Union density indicates the percentage of workers within a particular labor market or company who are members of a union. It is an important metric because high union density can lead to more effective collective bargaining, potentially resulting in better wages, benefits, and working conditions. This contrasts with a low union density, which may reduce a union's leverage in negotiations with employers.
The decline in U.S. union membership has been observed over several decades, with the proportion of U.S. workers belonging to unions decreasing significantly since the early 1950s. Various factors, including changes in the legal environment, shifts in industrial sectors, globalization of the economy, and cultural attitudes, have been suggested as reasons for this decline. Additionally, union membership in the United States is lower compared to many other high-income countries, partially due to different legal frameworks and societal views on unions.