How did the rise of big business lead to the formation of labor unions?

The rise of big business led to the formation of labor unions in at least two ways.

First, big businesses had more leverage over workers than little shops did. Therefore, workers felt that they needed to get leverage of their own. For this reason, they tried to form "big labor" to combat "big business."

Second, the rise of big business led to lower pay and poorer working conditions for workers. Jobs at the large companies ...