The United States was already deep in to the depression, and were mainly concerned with domestic issues at the time. Not to mention a strong isolationist social mindset.
because United states :Unites
It depends on what unites states you speak of.
Yes
No
50
16000 slaves were in the united states
United States is commonly used as a noun, but it can function as an adjective. For example: The Unites States Navy (describing which Navy) The United States border (specificing which border)
To work
50
It is New England
Obama
mostly protestant