Choosing 'English (United States)', or 'English (Canada)', in Windows' 'Region and Language' settings selects 12-hour clock formats for the Short and Long times by default, so it looks as if that is the 'standard' way of displaying time over there.
I was first introduced to the 24 hour system in the air cadets many years ago. At that time there was no colon placed between the hours and minutes, so the time of this post would be 0854 and not 08:54.