Up to and including 1880, the country had a frontier of settlement but at present the unsettled area has been so broken into by isolated bodies of settlement that there can hardly be said to be a frontier line.–Superintendent of the Census1890In the quote on the left, “isolated bodies of settlement” refers to 

The increase in settlements in the west caused the frontier line to disappear.

Explanation: The finishing of the railways toward the West after the Civil War opened up vast regions of the district to settlement and monetary improvement.

The East settlement changed the Great Plains. The gigantic groups of American buffalo that wandered the fields were mostly cleared out, and ranchers furrowed the natural grasses to plant wheat and other crops. The buffalo loss had a great impact to the American natives and the development of white settlement influenced in the West.

for the 2 countries u can do china and america because america has a democratic government while china has a communist government.

a democracy is a government run by the people either by directly voting or indirectly by electing representatives. an oligarchy is a government run by a few or a small group of people. a democracy and oligarchy are similar because both in an oligarchy and an indirect democracy, a small group of induvial determine the laws for a large group of people they are different because in an oligarchy it is easier to control and they do not have to answer to a large number of people in the country, unlike a democracy where they do have to answer to a large number of people an county that is a democracy would be the united states. a country that is an oligarchy would be the china.

i believe the answer is a