Final answer:
Unions faced with various challenges may opt for amalgamation or absorption in efforts to strengthen their bargaining power and ensure survival, especially with the U.S. having a legal environment that has become less friendly toward unionization over the years.
Step-by-step explanation:
Motivated by a need for stronger bargaining positions, a desire to avoid jurisdictional disputes, the decline of some U.S. industries, and the need for self-preservation, unions may choose either amalgamation or absorption. These strategies allow unions to bolster their strength and remain relevant in an environment where labor laws may not be as supportive of unionization as they are in other countries. The passage of the National Labor-Management Relations Act in 1935 once facilitated the rise of unions in the U.S., but subsequent legislation, like the Taft-Hartley Act of 1947, made it less hospitable for union membership and organization, contributing to a decline in union membership.