Because many believed there could be gold and many other riches that were undiscovered and also wished in claiming new land for wars in case another broke out
During Jefferson's time, only white male property owners could vote. During Jackson's time, most states allowed white males to vote even if they didn't own property.
WWII was more involved and global than WWI because WWI was mainly between Europe until the Americans got involved at the very end, While WWII was fought between everyone in Europe, America, Japan, Italy, Germany and the Soviet Union(Russia).
The middle ages were a period in Europe dating from the collapse of Roman empire in the west around the 5th
Tendency to view something in a particular way (I think)