Students returning to school this week across New York state should have plenty of room and no problem finding a seat. That’s because enrollment numbers are expected to be at an all-time low since the early 1970s.

There were 2.6 million students in public schools last year, down from a high of 3.5 million in the early ’70s and from another high of 2.9 million during a population rebound for the 1999-2000 year.

But since then, the state’s pupil enrollment count has been dropping steadily, according to a report released Tuesday by the Empire Center, a fiscally conservative government watchdog group. (The report also noted that statewide nonpublic school enrollment has been decreasing even faster than public school enrollment in New York.)

Despite this, education costs are still climbing in New York.

Only 100 of New York’s nearly 700 school districts have had net enrollment growth since 2007-2008, according to the report. That downward trend is expected continue, if one looks at U.S. Census data, birth rates and migration trends. At this rate, New York state’s student population will soon be at levels last seen during the 1950s.

The dropping enrollment continues even as pupil numbers in the rest of the country continue to rise, underscoring the ongoing population loss in upstate New York.

While New York’s enrollment fell by 10 percent since the turn of the 21^st century, the national pupil count has risen 7 percent, noted E.J. McMahon, the Empire Center’s founder and research director who authored Tuesday’s report.

The drop in part reflects the ongoing out-migration of New Yorkers to other states.

And it raises questions about why education spending in the state keeps growing even as there are fewer students to teach. New York tops the nation in school spending at more than $22,000 per pupil, which is 90 percent above the national average, according to U.S. Census data.

McMahon said the report suggests that it’s time for policymakers to think of innovative solutions. “Let’s stop debating finances, management and policy in a vacuum,” he said.

He believes that more flexibility for rural schools or regionalization could be one answer as would easing some of the regulations surrounding teaching hiring and assignments.

“What’s troubling is that it just goes up,” Jonathan Drapkin, president of the research group, Hudson Valley Pattern for Progress, said of education costs.

McMahon’s report, which uses state Education Department data, also depicts a tale of two states. While upstate is steadily losing pupils, New York City’s pupil numbers have remained stable over the years, hovering at just over 1.1 million. That’s the nation’s largest single school district and it’s reflective of New York City’s ongoing growth, fueled largely by immigration.

Immigration has also helped bolster pupil numbers in a few select upstate cities that haven’t seen large losses over the years including Albany, which serves about 9,500 students.

Areas in central and western New York, though, have seen notable drops with many losing between 10 percent and 25 percent of their students over the last decade.

The loss is especially acute in some the smallest, more remote districts. The Long Lake school district in the Adirondacks is starting this year with 71 pre-K-12^th grade students, down from 130 in the 1980s.

Numbers in the Capital Region overall have dropped slowly, according to the report. But even Saratoga County, with heavy real estate development, has seen a slight loss of pupils over the past decade.

Likewise, in the Hudson Valley, which includes Columbia and Greene counties, numerous elementary schools have closed over the past decade, Drapkin noted.

The report notes that outside of New York City there have been “pockets of  growth”  that are either in affluent suburbs like Rye and Mamaroneck in Westchester County or in “struggling upstate cities such as Albany and Syracuse,” as well as some inner ring suburbs.

Enrollment in Albany hit a low of 8,170 in the 2008-09. But over the next eight years the district grew by nearly 1,500 students, spokesman Ron Lesko said. The district also has had an influx of immigrant and refugee students. Many need extra help learning English, which adds to the cost.

That helps explain why education costs are rising in many districts, said Michael Borges, executive director of the state Association of School Business Officials.

“Increases in high need students, like English language learners, students with disabilities and those living in poverty, have offset the overall decline in the number of students,” he said.

But he added that schools also face increases in employee benefit costs like pensions and health care, which have negated any savings from fewer students.

Contracts for teachers and other unionized school employees typically include fringe benefits that have to be bargained if they are going to be reduced. Additionally, most teachers’ contracts include annual longevity increases that run for 20 years.

Similar contracts are in place for other public-sector unions such as municipal police and fire departments, noted Drapkin. That adds yet another “legacy” cost that communities are saddled with even if as fewer and fewer taxpayers contribute to the system each year.

“If you keep losing population,” Drapkin said, “it’s not sustainable.”