The Carson-Douglas rivalry has long been recognized as the best, and most-heated, rivalry in the area.USA Today High School Sports has taken notice.The publication is conducting its Rivalry Nation competition to determine the best high school rivalry in the country. The winners will receive $10,000 to be split between the school's athletic departments.Carson and Douglas made the cut for the state competition, along with Bishop Gorman-Palo Verde and Moapa Valley-Virgin Valley."All of these rivalries represent decades, and sometimes more than a century, of the greatest competition, and plenty of bad blood," the USA Today website stated. "But now those communities …