By almost every barometer, and at every level, football is the most popular sport in the country.
Yet until relatively recently the opportunity to throw, catch or kick a football in a high school competition had been largely a males-only activity.
Over the past decade, a growing number of girls have decided to tackle youth football -- and flag football leagues have emerged in several states.
This past spring, public schools in New York City and the District of Columbia began offering flag football as a varsity sport for girls, joining Florida, where it has been a varsity championship for 10 years, and Alaska.
"Football is kind of the last frontier for girls in sports," said Seminole Ridge (Loxahatchee, Fla.) coach Austin Bowe, whose team won the 2012 state championship. "It's not tackle, but it requires a lot of skills and knowledge of the game."
The biggest difference, however, between girls' flag football and another emerging high school, sand volleyball, is the issue of scholarships.
In sand volleyball, the push for the sport has come from the top down, as the NCAA sanctioned the sport this past season and Arizona followed suit as the first state to offer it at the high school level.
In flag football, the momentum seems to be coming from the grass-roots level. More and more high schools are playing flag football, with the hope that the NCAA will eventually offer scholarships.
"I was born too soon," joked Hannah Schaible, a quarterback for Dr. Phillips (Orlando), who was Florida's Player of the Year as a sophomore in 2011. "I think flag football will become an NCAA sport at some point, but it will be too late for me to play."
Morgan Lauer, the quarterback for Seminole Ridge, which beat Dr. Phillips 20-13 in this year's state final, first started throwing footballs around at age 5.
"I hope the sport continues to grow," said Lauer, who completed 76 percent of her passes this year and tossed 66 touchdowns to earn the state's Player of the Year honor. "I also play volleyball. But if I had a choice for college, I would definitely play football."
Florida is still the only state with a high school championship in flag football. Although the sport has only been offered for a decade, it already ranks eighth out of 20 sanctioned girls' sports in terms of number of participants (5,538). This past season, 192 Florida schools competed in flag football, up from 80 the first year.
But some women's sports advocates call it a dead-end activity. Flag football is played only at the club and intramural level in colleges, and no professional outlets exist.
"No one is saying flag football isn't a great sport to play," said Neena Chaudhry, the senior counsel at the National Women's Law Center. "But if you're going to add a varsity sport, it is relevant if that sport is going to provide the same opportunities as the boys have. In Washington, D.C., all the varsity sports for boys do offer scholarships at the college level. So, to then add flag football as opposed to a sport, like volleyball or soccer, that does allow girls to get college scholarships is not equitable."
Bowe is confident that the sport will spread throughout the country and eventually become an NCAA sport.
"Anywhere flag football starts, it tends to stay," Bowe said. "The girls love it. In seven years of coaching, I've never had one girl quit flag football."
In Alaska, only one of four regions offers flag football. But Russ Schreckenghost, the state's associate director for high school sports, said the sport is very popular in Anchorage.
"It's entering its seventh year, and more girls play football than basketball in Anchorage," said Schreckenghost, who added that at least one other region has expressed an interest in adding the sport. "There are schools that have more than 80 girls [playing] flag football."
Because of the state's extreme winters, flag football is played from July to October in Alaska.
In Central Texas, flag football has existed as a spring club sport since 2009. Teams typically have one practice and one game per week, and are open to any girl who wants to try out in the Leander and Round Rock school districts.
Meanwhile, states such as Virginia and Arizona have a large number of girls playing on the youth level.
The sport has long been a popular intramural pursuit for both males and females on campuses across the country.
"Flag football is huge in college," Dr. Phillips coach Anthony Jones said. "I graduated from the University of Florida in 2001, and when I was there, everyone played flag football. We had co-ed leagues, sorority leagues, frat leagues ... They even traveled around the state and the country for tournaments."
More than 200,000 players competed on women's and co-recreational teams last fall at 250 participating schools, according to the American College Intramural Sports (ACIS), which has hosted an ACIS Flag Football program and women's collegiate division National Championships each fall since 1980.
The rules for flag football are virtually the same as tackle football except that it is seven against seven, players don't wear helmets or pads, and the field is usually 80 yards instead of 100 yards. Teams play two 20-minute halves and, instead of tackling, a defensive player must pull a flag attached to the ball carrier's waist.
Flag football is a non-contact sport in theory, but collisions do happen.
"There's a lot of contact when girls are up in the air challenging for footballs," Bowe said.
Gary Pigott, the Senior Director of Athletics for Florida's high school governing body (FHSAA), said flag programs were started by many schools that were seeking to balance Title IX and gender equity, especially in large metropolitan areas where a large number of boys play tackle football. In surveys in Florida and several other states, female students strongly favored adding flag football over field hockey, lacrosse, water polo or badminton.
"We were basically reacting to our member schools," said Pigott, who added that the feedback over the past decade has been overwhelmingly positive. "We wanted to provide girls in another sport an opportunity to play."
According to Pigott, it is relatively inexpensive to field a team, since the flags and footballs are the only necessary equipment. He also said that most every school has at least a practice field large enough to play flag football.
Pigott and others at the FHSAA have talked to administrators in New York, Texas and Alaska, who have called seeking advice on how to grow the sport.
But can this sport grow enough that it will one day be sanctioned by the NCAA, as sand volleyball was this year? According to Gail Dent, a spokeswoman for the NCAA, the organization has received inquiries but no formal requests to add flag football. "To date, there has not been a proposal submitted for flag football to become an emerging sport," Dent said.
Piggott, for one, feels it's just a matter of time before flag football gains a foothold. "If any sport becomes popular enough," Pigott said, "they'll certainly respond."