This song was written in the dark days of the depression and sent the message that the United States was all one and that it had to work together to overcome the problems it faced. The man who wrote...
We say "in accordance with" or "according to" in slightly different circumstances. According to makes a reference to a source of information, while in accordance with explains an action in reference...
The Land of Opportunity was a nickname for the United States, especially during the waves of European immigration in the 19th and early 20th centuries.