On a cool and rainy afternoon during the first week of classes at Centennial High School in this well-to-do Baltimore suburb, about 50 members of the boys' cross-country team sauntered across the parking lot for their after-school run. Meanwhile, about 30 kids in helmets and pads were going through drills on the pristine artificial turf field at the school's hillside football stadium. "It used to be the other way around," said Al Dodds, Centennial's cross-country coach, who has 64 boys on his team this year. "Now, there's a small turnout in football and cross-country is huge." Across the athletic complex, a practice football field sat empty, even though it was recently mown and painted with yardage lines and hash marks. In years past, the junior-varsity team would have been relegated to that grass field. But on this day they had the stadium to themselves, as they will for every practice this fall. Centennial isn't fielding a varsity football team because not enough kids signed up to play. The situation at Centennial — where a long history of losing has dampened students' enthusiasm for football — is unique to this part of central Maryland, but there are plenty of similar examples around the U.S. Participation in high school football is down 3.5 percent over the past five years, according to the annual survey by the National Association of State High School Federations, or NFHS. The decline would be much steeper if not for a handful of states in the South and the West. Throughout the Northeast, the Midwest and the West Coast, in communities urban and rural, wealthy and working-class, fewer kids are playing football.