== Lead (Lede?) == 

 I don't know what standard style is here, but it seems to me that the intro for this article is too long, and includes extraneous, specific information that is better covered in the article body: 

 *In the second sentence (first paragraph), we do not need "and Washington, D.C., the capital district".  D.C. is already mentioned in the preceding sentence and is relatively insignificant to the geography of the country. 
 *In the last sentence of the first paragraph, we do not need "or insular areas".  This is an unnecessary distinction to make so early on in the article. 
 *In the first sentence of the second paragraph, we do not need the parenthetical "(9.83 million km2)".  The U.S. does not use SI units and the area in km is already provided in the infobox, thus inclusion in the lead is redundant. 
 *In the same sentence, it is completely unnecessary to point out that the U.S. ranks third by land area.  This is extremely pedantic, especially for the second paragraph of the article. 
 *In the last sentence of the second paragraph, either nominal GDP or GDP at PPP should be picked for world comparison.  Including both is redundant. 
 *In the first sentence of the third paragraph, the phrase "probably of Asian descent" should be eliminated.  Besides the fact that it's only "probably" and thus cannot be important enough to include in the article lead for that reason alone, it's just not significant enough to occupy such prime real estate. 
 *In the last paragraph, second sentence, slavery should come as the first reason for the civil war, since it was the primary reason for the war's occurrence.  Describing the north as "industrial" and the south as "agrarian", while true, is too pedantic for the article lead (this level of specificity would be fine for, say, the lead in the American Civil War article). 
 *In the last paragraph, sixth sentence  I'm not sure that being a founding member of NATO is of such importance that it merits inclusion here. 
 *Finally, the last sentence has awkward construction.  A specific fact is given to show the country's military dominance, but its economic, cultural and political power are simply asserted.  This "un-parallelism" should be fixed since the U.S.'s cultural and economic achievements are certainly as, if not more, important than its military ones, and both their placement in the sentence and lack of a specific example makes it seem as if military might is the chief characteristic of the country. 

 These are obviously simply suggestions, and obviously people disagree with some of them since I've been reverted a few times when trying to implement them.  However, I wanted to see what other people thought.  I personally think that shortening the lead by excluding extraneous details will make the article appear much less intimidating and much more streamlined.  The lead is often the most-read portion of an article (besides the infobox), so it's important to get it right.