What factors led to the second industrial revolution?

How did the completion of the transcontinental railroad change the lives of american citizens? a-it increased the wealth of all americans and enabled them to travel more. b-it made cross-country travel too expensive for ordinary americans. c-it decreased the safety of americans who moved to settle the plains. d-it shortened travel time between the east and west for all americans.

The internal combustion engine was an innovation of

In some african american communities, unemployment was as high as percent.