The Great Plains are primarily used for:
The Bill of Rights consists of the first ___ amendments.

The Battle of Gettysburg (1863) was important because:

Abraham Lincoln issued the Emancipation Proclamation in:

The cotton gin was invented by:

The Declaration of Independence was primarily written by:

The Louisiana Purchase (1803) doubled the size of the US. It was purchased from:

The 13th Amendment:
The first permanent English settlement in America was:
The map below shades each state by how its population changed between the 1930 and 1940 censuses. The country as a whole grew by 7.3 per cent over that decade.
Five of the six states shaded as losing population form one block on the Great Plains. What best accounts for that pattern?