1. more para of the interior geography of North America were mapped.
2. The Americans "realized" that from the Atlantic ocean to the Pacif Ocean, there was no water passage.
Do you have a specific civilization you are asking about? Or are we just implying on what we think makes best for a beginning of one?
I would like to think that the answer to your question would be James Monroe. I'm sorry if this doesn't help
A. The United States was occupied with domestic concerns during the Great Depression.
Many other countries were going through their own depressions, especially Germany with it's hyperinflation, so increased trade wasn't a thing. Nazi Germany wasn't fully in power yet, and communism, although not seen as a Cold War threat yet, was not tempting to the US.
