The Most Significant Events during 1789-1975

After a review of United States' history from 1789 to 1975, I have identified what I believe are the sixteen most significant events of that time period. The attached sheet identifies the events and places them in brackets by time period. The following discussion provides my reasoning
for selecting each of the events and my opinion as to their relative importance in contrast to each other. Finally, I have concluded that of the sixteen events, the Civil War had the most significant impact on the history of the time period in which it occurred and remains the most
significant event in American history.
The discussion begins with bracket I covering the period from 1789-1850, and pairs the number one seed in the bracket "Mexican-American War" against the fourth seed "Louisiana Purchase".
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