Boston Public Schools spends more per student than any other large school district in the country, according to the latest figures from the US Census Bureau, a new distinction that reflects how BPS’s budget keeps growing even as student enrollment continues to decline.

The city’s highest-in-the-nation cost, of $31,397 per student during the 2020-21 school year, represented a nearly 13 percent increase from the previous year, or about $3,600 more per student, according to the census, which examined spending in the country’s 100 largest districts.

During that same period, BPS enrollment dropped by about 2,500 students, according to the state’s annual Oct. 1 head count.

Yet for all the money BPS is spending, many education advocates, parents, and students are bewildered at how little the district generally has to show for it. State standardized test scores are low, huge gaps in achievement exist between students of different backgrounds, and the district had to aggressively fight off a state takeover last year.

And on a daily basis, students make do with chronically late school buses and learn inside rundown buildings that are several decades old and are in dire need of upgrades or replacement.

“The question we should all be asking the mayor, superintendent, and school committee is, ‘Are we OK with the results that we are getting for this sort of investment?’ ’’ said Ross Wilson, executive director of the Shah Family Foundation and a former BPS deputy superintendent.

Across the nation, school districts during the 2020-21 school year experienced the largest year-to-year increase in per-student spending in more than a decade, according to the Census Bureau. Like BPS, districts nationwide grappled with a significant decline in student enrollment during the first part of the pandemic.

But BPS saw its per-student spending levels increase twice as much as the national average of 6.3 percent. That enabled BPS, which previously ranked second, to surpass New York City Public Schools, the longtime front-runner in the national rankings, which had a more modest increase.

New York now ranks second with per-student spending at $29,931, followed by Washington, D.C., at $24,535, Atlanta at $18,492, and Chicago at $18,216. The 2020-21 school year was the most recent year examined by the Census Bureau.

Cities and states in the Northeast tend to have higher per-pupil spending than in the South, according to the Census Bureau, because the cost of living is generally higher and so are wages. The average teacher pay in Boston was $104,813 during the 2020-21 school year, according to the most recent state data.

Boston’s growth in per-student spending comes amid a turbulent time for the district, which has lost 8,000 students over the past decade and is working under a state-mandated district improvement plan to address a wide variety of problems.

Among the fixes, the state is demanding that BPS develop a long-term master facilities plan by December to modernize the district’s buildings, many of which lack gyms, libraries, and cafeterias. Underenrolled campuses dot the district, prompting critics to call for closures and consolidations to save money. But school closures have long been met with resistance by students, parents, and teachers.

Consequently, the district has spent millions in recent years to support schools with declining enrollment, prompting fiscal watch dogs to ask whether those dollars could go further in supporting programs for students if the district consolidated more schools and vacated more buildings.

The district, which currently operates about 120 schools, has closed or merged about three dozen over the last 15 years, but it also has expanded and relocated several other programs and created new ones during that time. Consequently, only a fraction of the buildings involved in those changes sit empty, and district leaders have indicated that some will be reactivated after renovations.

Meanwhile, state standardized test scores are low: Just 29 percent of students in grades 3-8 met or exceeded grade-level expectations on the MCAS last spring and 24 percent scored at those levels in math. More 10th-graders met or exceeded grade-level expectations: 47 percent in English and 41 percent in math. And huge gaps in achievement exist among students of different racial backgrounds.

Max Baker, a school district spokesperson, said the district was unable to comment specifically on the Census Bureau’s analysis because district administrators were unfamiliar with the methodology’s details. BPS contends that according to its own methodology, per-student spending was much lower for the 2020-21 school year, $21,700, but has been rising steadily to an expected $28,800 per student next school year. BPS based its calculations on spending from the city’s general fund.

“As a result of budgetary increases and declining enrollment, per-pupil spending has increased over the past four years to meet student needs,’’ he said in a statement.

BPS spending will likely increase again next year. The City Council is expected to vote in June on BPS’s $1.45 billion budget proposal for next year, which is up more than $70 million from this year — a request that some councilors have greeted with skepticism.

City Councilor Erin Murphy, a former BPS teacher, said the schools’ repeated requests for budget increases while student enrollment declines doesn’t add up and she also questions how the district is spending its money. For instance, she noted, BPS isn’t devoting enough for athletics, extracurriculars, and before- and after-school programs, even though it has ample money to pay for it.

“Where’s the money going?’’ said Murphy, noting schools often still have to scramble to fill in budget gaps. “Schools shouldn’t have to rely on fund-raisers to provide students with basic things like buses for field trips, smart boards for classrooms, and science supplies.’’

Vernée Wilkinson, director of the family advisory board at SchoolFacts Boston, a nonprofit that works with Boston families, said she doesn’t know whether Boston’s national ranking and how it compares to other large districts matter as much as whether “families are getting the return on the investment that’s being made.’’

“Those are life-changing numbers,’’ she said of BPS per-student spending levels, adding that “those are the type of numbers you pay tuition with.’’

But Wilkinson is skeptical that BPS is making the most of the money, noting parents her organization works for are concerned about late buses, a lack of quality programs for Black and Latino students, and struggles to get adequate services for students with disabilities.

“Students and families continue to deserve so much more than what they’re receiving,’’ she said.

Ruby Reyes, director of Boston Education Justice Alliance, said she thinks BPS needs more money to improve the educational experience at every school, which should include art, music, science, psychologists, certified librarians, and clean and well-maintained buildings. And she also notes that Boston students are expensive to educate. Almost a third aren’t fluent in English, for instance, and more than 20 percent have disabilities.

“Those bills go up and it’s not like inflation suddenly stops,’’ she said.

James Vaznis can be reached at james.vaznis@globe.com. Follow him on Twitter @globevaznis.