Question: What was the longest war in the us?
Disambiguated questions and answers: question: What was the longest war that the US participated in?
What was the longest was that took place in the US?
answer: Afghanistan War
Fourth Anglo-Afghan War
US War in Afghanistan
War in Afghanistan
Ohio War
Northwest Indian War
Little Turtle's War
Natural Questions answer: War in Afghanistan (from the Wikipedia article "List of the lengths of United States participation in wars")