One by one, the prospective charter school founders made their pitches.

The campus focused on social justice would provide a high-quality middle school in a city that lacks them. A year-round high school in a low-income D.C. neighborhood promised to focus on students’ emotional needs and cultural competence to raise academic performance. And there was the all-girls high school, and the elementary school that wants to offer Arabic.

Applicants made their cases last month for 11 new charter schools in the District to open for the 2020 school year. They hope to participate in the education of a city with a growing student population and flush government coffers.

But how many more campuses can the District handle?

While new schools in the charter and traditional public sectors are opening, other campuses sit more than half-empty, facing budget cuts as their student populations dwindle. The problem is most acute in the upper grades in low-income neighborhoods, where charter schools are plentiful and a large percentage of students commute across the city seeking options they think are better than the schools in their own neighborhoods. In some wealthier areas, schools sit above capacity, strained by having too many students.

“You are hoping to enroll in Ward 7 and 8, and you know we have a number of under-enrolled high schools — both charter and D.C. Public Schools,” Saba Bireda, the vice chair of the D.C. Public Charter School Board, said to an applicant hoping to establish a school in one of the two poorest wards in the city at a hearing last month.

“How are you sure that there is sufficient demand for this school?”

The charter school board, whose members are appointed by the mayor, votes each year on whether to approve new campuses. Other cities and states have a cap on charter schools — which are publicly funded but privately operated — that can open. The District does not.

The District is home to 123 charter schools, which educate nearly half of the city’s 98,000 students who attend public schools.

Last year, the charter school board approved just one of four applicants that wanted to open a school. In 2017, the board received seven applications and approved four.

The traditional public school system is also expanding. It opened an all-boys high school in 2016 and is opening a specialized high school next school year in Southeast Washington.

“We are looking for schools that will bring quality choices to the city. We want [applicants] to demonstrate to us that there is a need for the school,” said Scott Pearson, executive director of the charter school board, who does not have a vote on the panel. “We hear the concerns about flooding the city, and we don’t want to be part of that.”

According to a city analysis, about a fifth of all school buildings are less than 65 percent full. And campuses in the traditional school system are even emptier.

That means many of the schools have small enrollments. There are 38 high schools across both sectors serving nearly 20,000 students.

With so many high schools, it makes it challenging for campuses to have robust course offerings and extracurricular activities to attract students. Paul Kihn — the city’s deputy mayor for education, who oversees both the traditional public school system and charter sector — said smaller schools are more expensive to operate. Some neighborhood schools are facing budget cuts for the coming academic year because their enrollment is projected to take a steep dive.

His office works with other government agencies to track projected enrollment growth. Enough empty seats exist to accommodate enrollment growth, according to Kihn. But the locations of those seats do not necessarily correlate with demand.

Kihn said the flood of charter-school applications shows the passion that exists to improve education, but he said it has also “given me pause.”

“As a city, we are thinking about the impacts that any school potentially opening has on an existing school,” Kihn said. “Our number one priority is making sure that the schools we have are getting better.”

Charter school applicants say many of the campuses with empty seats are low-performing. They say waiting lists indicate strong interest in high-performing schools — and they hope to meet that demand. Myron Long, founder of the Social Justice School, a prospective middle school, said he hosted a pilot class last summer for students and has received feedback from families.

“There is a need for strong middle schools in the city,” Long said. “At the Social Justice School, students will be challenged academically but will also learn to make the world a better place.”

Justin Lessek, founder of the Sojourner Truth School, a prospective middle and high school using the Montessori model, said he focused on the demand for the learning style his school would offer. His 700-page application, which included letters from parents who said they would enroll their children in the school, showed that waiting lists at the District’s Montessori elementary campuses are longer than for other schools.

“Currently, there is no pathway for continuity of approach for Montessori families all the way through high school,” Lessek said. “We can fill this much-needed niche for families.”

Mary Filardo — executive director of the 21st Century Schools Fund, a D.C. nonprofit organization that examines school facilities throughout the country — said she thinks the District should limit the number of charter schools allowed to open. Allowing more schools to open, she argues, could destabilize a system with schools already struggling to enroll students.

“There is no place where we need more charters,” she said. “Why are we coming up with a system that costs us more?”

Kihn, who does not have a say on which charters are approved, declined to comment on whether he thinks there should be a cap but said he was most interested in schools that offer programs lacking in the city. One example: Aspire to Excellence Academy, a prospective school that would offer preschool and adult education.

“It is our collective responsibility,” he said, “to consider the real life impacts of any decision we make as a community.”