Em-dashes 

Thanks for pitching in on the United States article. I noticed that you added spaces around a couple of em-dashes. That actually goes against our Manual of Style: "Em dashes should not be spaced." Also, whenever considering such a stylistic change, look through the whole of the article to see if the present style is applied consistently (in the case of the United States article, unspaced em-dashes have indeed been applied consistently). If you do find that the style is consistent, there should generally be a compelling reason—not just a personal preference—for any change. Regards.