The United States of America is constantly changing. Each president makes changes that shape this country. Three presidents that made some of the most important contributions to our nations history were, George Washington, Abraham Lincoln, and Franklin D. Roosevelt. They were involved in the three most important wars fought by the United States of America. George Washington was a great president who led this country to independence. He fought the British until they surrendered. The United States won the war. Furthermore, he appointed peo ....