Define country, because the American government is actually one of the oldest continuous governmental systems in the world. Certainly the oldest republic that isn’t a micro-state.
Now if you want argue that France, for example, is an older country than America because there’s been a fairly stable region largely called France for several centuries you can, you’d just be wrong.
Now if you want to start talking about nations that’s different, but also a much, much blurrier subject in general.