For nearly half of its relatively brief existence, the United States has been actively involved in armed conflict, whether at home or abroad. Here is a closer look at wars involving the U.S. military. The longest continuous war in U.S. history, depending on whom you ask, is the current war in Afghanistan. However, it can be argued that the Vietnam War was far longer. Why the confusion? The U.S. never officially declared war on North Vietnam, Laos or Cambodia, and heavy U.S. fighting didn’t start until the ’60s. Check out some other facts to see the history of United States in armed conflicts.
Source: War and Peace: History of the U.S. in Armed Conflict