School leaders in Arlington are struggling to accommodate about 1,000 new students in the coming school year, a crunch that's sending school officials scrambling for teachers, assistants, administrators, equipment and relocatable classrooms. Over the summer, 25 new relocatable classrooms have been installed in anticipation of the first day of class. If growth continues on projection and no changes are made to current capacity, school officials estimate, Arlington public schools will be at 120 percent capacity in 2018 with a shortage of 4,400 seats.

"It's quite a problem in a fully developed county to be able to handle this," said John Chadwick, assistant superintendent. "We're not like Loudoun where we can go out and build new schools on green fields."

School officials are working on plans for construction of two new elementary schools and additions to three existing elementary buildings. Earlier this year, new boundaries were approved for elementary schools to accommodate the rapidly growing student population in the south part of the county. And School Board members are anticipating yet another boundary change for high schools in the near future. The need for boundary changes has become such a pressing concern that school officials even created an online game where people can draw their own boundaries to meet capacity needs.

"It helped people understand how difficult it is to redraw boundaries," said Frank Bellavia, communications director for the county school system. "And part of the process was letting parents know that more boundary changes are likely in the near future."

WHEN SCHOOL DOORS open this year, Arlington Public School will have about 24,000 students. By 2018, that number is expected to spike to about 28,000 students. By 2023, enrollment could be anywhere from 27,000 to 31,000, a crush of new students that has county leaders worried that Arlington's classrooms could become unwieldy. The largest projected increase is expected in the county's elementary schools, which are expected to add about 1,500 students in the next five years. The steepest increases have been in the south part of the county, where elementary school enrollment has increased about a 50 percent in the last five years.

"We can't build for every seat that we would like to build for, and we probably shouldn't anyway because the population might start to decline again at some point," said Chadwick. "And we can't build seats as quickly as they are needed."

This year, Arlington taxpayers will spend an extra $10 million to handle the growing enrollment in a county that spends $18,675 for each student — the highest per-pupil spending in the region, according to an analysis by the Washington Area Board of Education. County taxpayers are currently paying for a new elementary school on the Williamsburg Middle School campus as well as an addition at Ashlawn Elementary School. In the coming years, School Board members are expected to consider renovations at McKinley Elementary School and Arlington Traditional School as well as another new elementary school on the Carlin Springs campus.

“We certainly couldn’t come up with options that had all of the new seats in one location because we need to add seats throughout the county,” said School Board Chairwoman Abby Raphael at a forum earlier this year. "So we knew we had to have a combination of new schools and additions. “

SINCE THE 1960s, enrollment trends have waxed and waned. The high-water mark was in 1961, when enrollment topped out at the all-time historic high of 27,000

The low point was in 1988, when the countywide enrollment was 14,000 — almost half of what it had been in the 1960s.

In the last 20 years, the county schools have become wealthier and whiter. In 1998, white students were about 41 percent of the student population. Today that number is 47 percent. And the number of students who qualified for free or reduced-price lunch in 1996 was 41 percent. Today that number has dropped to 31 percent.