How can I change the order of the list of countries provided by the Countries module? I have a Drupal 7 site that uses the Countries module.  I would like to show the United States first in the list and the rest of the countries then in alphabetical order (by default, the module displays all countries in alphabetical order).  This is a common feature on many sites so I'm hoping there's an easy way to do this.
It's a shame Sumeet didn't continue his answer, as he got so close, but here is the alter hook:

function HOOK_countries_alter(&amp;$countries) {
  $US = $countries['US'];
  unset($countries['US']);
  array_unshift($countries, $US);
} 


It copies US, removes it from the list, and attaches the copy back to the top.

You don't say in what context you use the module. I verified that it does what it should on a country-field.