Why is James Monroe considered the last founding father?

James Monroe is often considered the last founding father due to his significant role in the early years of the United States, particularly as the fifth president from 1817 to 1825. He was a key figure in the American Revolution, served as a diplomat, and played a crucial role in shaping foreign policy through the Monroe Doctrine. His presidency marked the end of the era dominated by the original founding figures, as he was the last to have actively participated in the revolutionary struggle and the formation of the nation. Monroe's leadership and policies helped solidify the principles established by the founding fathers, making him a symbolic bridge to the new nation.