Final answer:
The coal mines and railroad yards in Pennsylvania had low labor activism during the early 20th century due to factors like violence, lack of legal protection, and a conservative political climate.
Step-by-step explanation:
The coal mines of eastern Pennsylvania and the railroad yards of western Pennsylvania were two industries that had low labor activism during the early 20th century. These industries were central to Pennsylvania's economy and home to large immigrant working communities. Due to factors such as violence, lack of legal protection, and the conservative political climate of the era, there were minimal efforts to organize workers in these industries.