Chicago Public Schools officials attribute this year’s overall bump in graduation rates — which show that more than three of every four students getting a diploma — to an increase in high school completion among African-American boys.

About 77.5 percent of students who started ninth grade for the first time in the fall of 2012 graduated from high school within five years — the time-frame commonly used in big urban districts, according to figures the district released Monday. That’s up from the class of 2016’s 73.5 percent for four- and five-year completion. The rate for students who finished in four years rose only slightly to 74.7 percent.

It’s the latest good news revealed in the days leading up to Tuesday’s start of classes for students in the country’s third-largest public school district, whose leaders have struggled mightily to right its finances.

About 20,000 students of the original 29,000 received a diploma in 2017. That’s up about 100 students from 2016, despite CPS’ overall enrollment tumbling 11,000 students last year to about 380,000. In 2011, CPS enrolled far more students — more than 400,000 — but counted just 18,446 graduates.

Chief Education Officer Janice Jackson said officials have focused on secondary education, keeping a close watch on freshman on-track rates — that is making sure ninth-graders show up for class and pass their courses. University of Chicago researchers have called on-track rates the strongest single predictor of graduation rates.

“You see higher numbers of students graduating across the board in all different types of schools,” said Jackson, who has set an ambitious 85 percent target by 2019. “They are making the mark and improving each year.”

Jackson also noted that graduation among African-American boys, who make up the largest subgroup within the district with 6,591 original ninth-graders, increased more than 5 percentage points.

“That’s significant for a number of reasons,” Jackson said by telephone. “They are one of our largest demographic subgroups, so dramatic improvements there are going to help the bottom line for the district. Every time we talk about student performance metrics, the achievement gap is always a focal area for both us as well as the public. And we’re just happy to see this is an area we can boast about.”

African-American students generally still lag behind everyone else with 71 percent graduating. Among girls, 79.5 percent graduate; among boys, 62.8 percent graduate.

And Jackson couldn’t yet say whether the uptick seen among African-American boys was connected in any way to an overall population loss of African-American families in the city and its public school system.

That same decline concerned Misuzu Schexnider of the high school equity advocacy group Generation All.

“There are many ways to increase an average graduation rate, and one way is to have less lower-achieving students,” said Schexnider, who wondered if the significant four-point rise comes “because all students are performing? Or is it because of a change in our composition?”

“Four percent growth in one year is something to celebrate — and something that also should raise concern. Let’s really look at where that came from.”

CPS has put a lot of effort into tracking students through high school to bolster their success, Schexnider said. And those efforts should be used by a district whose school closing moratorium is about to expire “not for punishment but to shine a light on inequity” to get at the “root cause of why certain groups of students aren’t performing as well.”

The graduation rate among Hispanic students rose to 80.7 percent; among white students, 88.3 percent; and about 94 percent of Asian students finished in five years.

Special-education students also saw gains from 61 percent last year to 63 percent in 2017.

Jackson said that open-enrollment neighborhood schools didn’t see as big a rise as last year, but the “trend is pointing in the right direction and very positive.”

Four high schools still graduate less than half their starting freshmen. Another 10 schools graduate between 50 percent and 60 percent of students. CPS has proposed rolling two of these high schools into a single Englewood campus.

The statistics did not include any of the so-called “options schools” that grab up students at risk of dropping out or who already have left high schools. Students who do get a diploma at those schools are counted where they first went as freshmen.