In 1890, When the Superintendent of the Census Announced That

In 1890, when the superintendent of the census announced that a stable frontier line was no longer discernible,
Americans were disturbed because

A) they knew that the Homestead Act would no longer do them much good.
B) they thought that there would be a renewal of Indian warfare.
C) the idea of an endlessly open West had been an element of America's history from the beginning.
D) many of them hoped eventually to migrate to the West.
E) they feared that an influx of new western states would strengthen the Populists and other radicals.