There is no single agreed-upon way of deciding what is a 'war' rather than an 'intervention' or occupation or police action or peacekeeping mission.
The United States has been involved in these major wars between 1900 and 2000:
World War 1
World War 2
Korean War
Vietnam War
(First) Gulf War
There have also been many smaller wars involving US military forces and casualties:
China (pre-WW2)
Philippines (1898 - 1910)
Philippines (1945 - 1950s)
Grenada (1983)
Panama (1901 - 1914, 1989)
Lebanon (1982 - 1984)
Honduras (1903, 1907, 1911)
Nicaragua (1907, 1910, 1912-1930, 1980s)
Russia / Soviet Union (1918 - 1922)
Germany (1948 - 1949) Berlin Airlift
Indonesia (1965)
Yugoslavia [Serbia, Bosnia, Kosovo] (1992 - 2001)
There have also been actions in US territories:
Oklahoma, Creek Indian War (1901)
Washington DC (1932)
Many additional actions have occurred. US military personnel have been killed in nearly all of these operations.
Afghanistan has been in 87 wars since 1896
a goose
One thing is that since the age of atomic weapons there has not been any more world wars.
There have been two World Wars, and Italy has been involved directly in both of them.
There have been wars since Before Christ (BC) and After the Death of Christ (AD). All wars of which nation?
there have been
2000
Practically all the wars, local or otherwise, in the Western world since the 16th century and almost all the wars on this whole planet since the 17th century. They are too numerous to count.
did it end in 1945 has there been anymore wars since the 2nd world war
Both World Wars.
Afghanistan has been in 87 wars since 1896
The United States has not declared war on another country since World War Two. All military adventures since then have been referred to as 'police actions'. Answer Yes, they are recognised as wars
The Indian Wars, World War I, World War II, Korea, Vietnam, Gulf War (1990), and the Iraq War.
a goose
a goose
No, the United States has not been in three world wars.
World War I, World War 2, Korean War, Suez, Falklands Campaign, both Iraq Wars, Afghanistan and various other skirmishes in between.