Data: US Participation in Major Wars

Listed below are the lengths (in years) of US participation in major wars in 20th and 21st century wars, and 18th and 19th century wars.

20th and 21st Century Wars

8.7

11.1

0.1

8.75

3.1

3.7

1.6

18th and 19th Century Wars

0.7

4

1.8

2.5

8.4

Source: wikipedia.org