Hello. You did not provide the excerpt to which this question refers, which makes it impossible for it to be answered accurately. However, I will try to help you in the best possible way.
A historic development that may have been addressed in the text is the strong industrialization that the country has undergone, which has attracted countless immigrants to work in the factories. In addition, the march to Oste stimulated the entry of immigrants more and more intensely. In this case, the author can position himself on how the country was built with the presence of immigrants, which contributed strongly to the ethnic and cultural diversity that citizens have. Thus, the author can affirm that both in the Golden Age and at other times, immigration is driven by economic reasons, marjoritically.
It became more assertive by the U.S. expanding its borders into Florida and through their foreign affairs that included the Monroe doctrine preventing Europe to interfere with Latin American political affairs.
The increasing toll on diseases have contributed to high death rates & life - long illnesses .
Answer:
used to help rebuild cities. retrained by the US military.