Final answer:
When trade unions joined together into national organizations, the tactics of labor changed by enhancing bargaining power, increasing coordination, and maintaining focus on local issues.
Step-by-step explanation:
When local trade unions joined together into national organizations, the tactics of labor changed in several ways. Firstly, it enhanced bargaining power on a national scale. By uniting, labor unions could negotiate with employers on a larger scale, increasing their influence and ability to gain favorable conditions for workers. Secondly, it increased coordination among labor groups. National organizations allowed for better coordination and collaboration between different local unions, strengthening their collective voice.
Lastly, the transformation also led to increased focus on local issues. While national organizations were formed, they still recognized the importance of addressing local concerns and advocating for workers' rights at a local level.