Final answer:
The conclusion of America's longest war is significant due to its historical impact, effects on global geopolitics and security, and raising questions about the war's effectiveness.
Step-by-step explanation:
The topic of the last troops exiting Afghanistan, ending America's longest war, is significant to discuss for several reasons. Firstly, it marks the end of a significant historical event; the two decades-long conflict impacted many lives and the legacy of U.S involvement there will be debated for years to come. Secondly, it affects global geopolitics and security, as the withdrawal of American troops has implications for regional stability and international relations. Lastly, it raises questions about the effectiveness of the war and the strategy of foreign intervention, prompting analysis of the war's objectives versus its outcomes.