What does abbott's recollection tell you about the changing frontier?

When Europeans arrived in America in the 1600s, the frontiers began moving west. As they continued spreading their land occupation, American Indians were moved west. In 1889, the  government transferred white  colonists the Indian land, breaking the promise, as these lands had been promised to Indians. The Indians tried to take over those lands to no avail. In 1890 the Bureau of the  Census stated there were no frontiers within the  country.

a plantation economy is an economy based on agricultural mass production, usually of a few commodity crops grown on large farms called plantations. plantation economies rely on the export of cash crops as a source of income.

i hope this : )

what are the reasons