Austria-Hungary had invaded and crossed over into, Serbia and Russia was in an alliance with Serbia, so they felt as though they had to help out. Hope this helps.
Answer:
The acquiring of the territories gave the United States justification to send out immigrants into those territories and settle the land along the trails created by traders and trappers beforehand. These immigrants and other workers then set up the Transcontinental Railroad to facilitate trade and transport back and forth from the west coast to the east.
Political realism is the policy that your looking for
FDR is known for his fireside chats
radio was much more common during that time and the method in which people got their news
