Registration is now open for National Night Out events in southern Denton County, including block parties and poster contests in Flower Mound. Each year, about 38 million Americans participate in National Night Out, a cohesive effort to promote crime prevention, police-community partnerships and neighborhood unity, according to a news release from the town of Flower Mound. Neighborhoods in large and small communities throughout southern Denton County get together with their local police officers each year and are planning for this year’s NNO, scheduled for Oct. 1.