Why did the number of settlers to the pacific northwest increase dramatically after 1880?

The completion of the transcontinental railroads.

Explanation:

One of the main reasons why the number of settlers to the Pacific Northwest increased dramatically after 1880 was the fact that the transcontinental railroads were completed around this date. The fact that the railroad was completed allowed people to move to the West more easily. It also allowed for the growth of cities and the establishment of new industries and businesses, which in turned attracted even more workers to the region.

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