The fate of any organization is largely a function of that organization's leadership. The "organization" of the United States is no exception to this rule. While he leads in the polls for the Republican party candidacy, it seems only appropriate that we understand and think about the type of leader Donald Trump would be for the United States.
I do not know Mr. Trump personally and I have never had the opportunity to assess his personality professionally (though I'd be happy to do so if he were willing). Thus, my views are based purely on watching his behavior.1 His personality is captured by his reputation, which is the sum of his behavior, and organized by a standard set of themes as follows.
We can look at both sides of Mr. Trump's personality. The Bright Side (how he typically behaves when he's at his best) and the Dark Side (how he typically behaves when he lets down his guard).
Beginning with the Bright Side we can expect Mr. Trump to be:
On the Dark Side we can expect Mr Trump to be:
In summary, what we can expect from Mr. Trump is what we have already seen and know about his reputation.2 What does this mean for the United States? People tend to vote for leaders in their own image. Thus, the personality of Mr. Trump also highlights the characteristics of those who will likely support and vote for him. As such, Mr. Trump's popularity in the polls also serves as an indicator of our current American culture.
Postscript (3/9/2016) - If you liked this article, you might also my discussion of Donald's Trump's Values.
1 Which is the same method everyone else uses, though I do have the advantage of being a trained personality psychologist with experience assessing lots of personalities.
2 It should be noted that the above assessment is comparing Mr. Trump to the population in general, and not the other Presidential candidates (some of whom may be very similar to Mr. Trump on a number of these characteristics).
I am grateful to Dr. Tomas Chamorro-Premuzic and Dr. Robert Hogan for their thoughtful suggestions and contributions to this post.