As a result of the development of the railroads, the effect on westward expansion was C. New commercial centers and communities emerged along rail lines.
Why was this so?
As a result of the railroads, people were able to move to the west in an easier and faster fashion.
When they did so, they set up communities along these railroads because those areas were quite accessible. Commercial centers were also set up to serve these people.
In conclusion, option B is correct.
Find out more on the railroads and western expansion at https://brainly.com/question/1313348.
