SAT Subject US History Practice Question 257: Answer and Explanation
58. The success of which of these nineteenth-century inventions was a direct result of the growth of the railroads?
C. Threshing machine
E. Colt revolver
Correct Answer: D
The railroad made the telegraph possible. The railroad carried people to distant locations, thus creating a need for long-distance communication and also sending people out to string the telegraph wires and build and staff the telegraph offices.