Fifth-grade safety patrol guards Chiara Ferrando, Sofie Craig and Shay Brewer, all 10, finish their morning patrol at McKinley Elementary School on Wednesday in Arlington. (Amanda Voisard/The Washington Post)

For as long as he can remember, Celso Amaya-Ventura has looked forward to being in fifth grade so he could join the safety patrol. His reading buddy in kindergarten was a patroller, as were the older kids who sometimes played with him at recess. The students in the neon green belts seemed to be everywhere at his Arlington County school — in the hallways, on his bus, at the front door.

“They are kind of like the leaders of the school,” Celso said.

Last week, it was finally his turn. Celso’s mother dropped off the 10-year-old on the first day of school in his new blue shirt — “the fanciest I had,” he said — so he could collect his belt and get in position for his first official job with the McKinley Elementary School safety patrol.

But the “Orange” bus was late that day, and Celso was left waiting on the curb until the morning bell rang. He had to go to class before he could escort the first-graders to their classrooms. “I didn’t get to do my duty,” he said.

Celso is taking part in a rite of passage that’s been shared by millions of children across the country for nearly a century — that early taste of authority and military ritual that’s known as the safety patrol.

More than 600,000 students in 32,000 schools nationwide are members of the safety patrol, according to AAA, which organizes the programs in partnership with schools and local law enforcement agencies. Participation is particularly high in the Washington region.

Fairfax County has as many as 10,000 patrol members each year. And in Montgomery, Prince George’s and Arlington counties, nearly every elementary school has a safety patrol, said Joe Beddick, manager for safety services for the AAA Mid-Atlantic Foundation for Safety and Education.

“Sometimes, we think, ‘Will this ever stop being the cool thing to be?’ ” said Kyra Wohlford, a fifth-grade teacher at McKinley and a former Arlington patroller. “It never has. It’s a tradition that’s lived on and on.”

AAA created school safety patrols in the 1920s to promote pedestrian safety amid increasing traffic.

The organization has awarded more than 400 “Lifesaving Medal Awards” since 1949 for patrol members who have saved children’s lives. Arlington student Inmar Castillo-Hernandez was one of five students in the Washington area and eight students nationwide to win the award this past spring after he prevented a pre-kindergarten student from running in front of a moving bus at Carlin Springs Elementary School.

Patrol members used to fan out into neighborhoods to help younger children cross the street in the blocks surrounding schools. Over time, due to broader safety concerns, most have moved in closer to school grounds and work with adult crossing guards and teacher supervisors, said Jennifer Davidson, AAA’s manager of traffic safety advocacy.

Many patrol members now volunteer on their school buses, helping students board safely and minimizing distractions for the driver.

The program also has increased its emphasis on leadership training. Jimmy Carter, Bill Clinton and several U.S. Supreme Court justices are among the patrol graduates touted by AAA.

“They start with their first badge as a safety patroller” and go on to jobs in law enforcement or public services, Davidson said.

Despite changes, many of the rituals remain the same. Children wear ranked badges and the same Sam Browne-style belts, named for a 19th-century British general who used the diagonal shoulder strap to help balance the weight of a sword.

For students at McKinley, the badge and the belt give them a chance to yell with impunity, as they holler the names and numbers of incoming school buses and mark the end of their morning shifts with a chorus of “OFF DUTY.”

In a class of 73 fifth-graders, 45 applied and were accepted to the safety patrol. They recited the patrol pledge at an assembly last spring. New recruits spent two weeks in training so they would be ready to go when school started Sept. 3.

On the second day of school, patrol members arrived early to get in position. One group of girls waited near the curb in front of the school with a hand-painted sign announcing the Kiss and Drop location. They opened car doors and greeted students, escorting the youngest ones to the front door.

Nearby, a group of boys was stationed at the end of the bus loop, moving bright orange cones away each time a school bus approached. Celso rode the bus that day, where his patrol duties started as a monitor for the middle section of the bus.

By the end of the week, there was one student who kept standing up and reaching out the window to grab at tree branches. “I had to give him a warning,” Celso said. Two second-graders who got into a fight on the bus will have to be separated for future rides. “I have to inform the other patrols that they can’t sit near each other to keep them safe,” Celso said. “Now I see how hard it is,” he said.

Some high points were giving directions in Spanish to a new student from El Salvador who had boarded the wrong bus and finally getting to escort the first-graders from his bus to their classrooms.

His goal for the school year is simple, Celso said: “To learn every student’s name and to gain their respect.”