Why is it important for us to understand the geography of our country?

Just a brief recommendation:  Elias Canetti wrote a wonderful book called Crowds and Power in which he discusses how every country's physical geography affects its "personality."  Germany has thick forests; England is an island, which reflects in its isolationist view; America, reflected in its two coasts, is a land of contrasting but compatible life-styles, etc.

Geography has an impact on many events affecting a country including cultural, economical, and historical events. By understanding the geography of our country, you will be better able to understand some of the events that have affected our country.
One example that can be given deals with historical events. Many Americans were shocked when World War I began. Geography has helped us tremendously when it came to war. Prior to modern forms of travel and technology, the United States was isolated from many countries by the Atlantic Ocean and the Pacific Ocean. The oceans served as a barrier helping to protect us from attack and invasion. It was easier for the United States to remain neutral and to want to stay out of world affairs because of our geographical location. We didn’t have to deal on a daily basis with too many countries surrounding our country. This wasn’t the case in Europe. It also was easier for President Wilson to want to have a peace treaty that wasn't so harsh on the Central Powers. The leaders of the other Allied countries, whose countries were much closer to Germany and who feared Germany becoming strong again, wanted to punish Germany severely.
Another example is the location and the development of cities. Prior to modern forms of transportation, many cities developed along major rivers, and especially where two or more rivers merged. Factories had to be located near water prior to the development of the steam engine, and being located near a river made it easier to ship products.
A third example is the development of culture. The Native Americans were relocated to the Great Plains because that area was considered a great wasteland. For a period of time, the Native Americans were able to develop their culture and tribal practices in relative isolation because people thought this land was undesirable. Of course, once minerals were found in these areas and Americans began to move into these regions, all of that changed. The Native Americans were forced onto reservations, and their way of life was destroyed once again.
Understanding the geography of any country will allow a person to have a better understanding of many of the cultural, economical, and historical events that have occurred in that country.
https://foreignpolicy.com/2013/04/16/how-geography-explains-the-united-states/

https://www.nationalgeographic.org/encyclopedia/north-america-human-geography/