Which advance accelerated the settlement of western regions of the United States and Canada during the nineteenth century? use of the cotton gin

Invention of the tractor

Construction of railroads

Introduction of irrigation

Correct answer is Construction of railroads

Explanation:

Construction of railroads is the correct answer as many historians have concluded that railroads did the most to the development of United States. Without them it is a question how the States would develop.

First option is not correct as it is connected more with the development of southern states.

Second option is not correct as tractor was introduced later.

Introduction of irrigation is not correct as irrigation was developed much earlier and didn't affect development of West that much.