22, according to Wikipedia: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;List_of_wars_involving_the_United_States" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;List_of_wars_involving_the_Uni...</a><p>Interestingly, none of them on their home territory.