Laughlin, Nevada, and Bullhead City, Arizona, are separated by a unique state line: the Colorado River. It's an interesting juxtaposition of cities, with the casino lights of Laughlin sparkling across the river from Bullhead City. Sixty miles upstream, just southeast of Las Vegas, Boulder City is prim, languid, and full of historic neighborhoods, small businesses, parks, greenbelts—and not a single casino. Over the hill from town, enormous Hoover Dam blocks the Colorado River as it enters Black Canyon. Backed up behind the dam is incongruous, deep-blue Lake Mead, the focal point of water-based recreation for southern Nevada and northwestern Arizona and the major water supplier to seven Southwest states. The lake is ringed by miles of rugged desert country. Less than half a mile downstream from the Hoover Dam and Lake Mead, another engineering marvel, a bridge spanning the river canyon and linking northwestern Arizona to southeastern Nevada, opened in fall 2010. It’s dramatically reduced traffic across the dam.