About 73 percent of D.C. Public Schools students graduated on time this year, another record high for a school system that struggled not long ago to graduate half of its students.

The graduation rate in 2017 marked a four-point rise from the previous year and a 20-point gain from 2011, when just over half of D.C. Public School students graduated within four years.  The school system fell just short of former Chancellor Kaya Henderson’s 2012 goal of getting three-quarters of students to graduate by this year. The district aims to have 85 percent of students holding a diploma on time by 2022.

The charter school sector, which educates about 46 percent of public schoolchildren in D.C., saw slight gains, with just over 73 percent of students graduating on time, up about a half a percentage point from last year.

Mayor Muriel Bowser credited some of the growth to the city’s increased investments in education

“These graduation rates are a reminder that when we have high expectations for our young people and we back up those expectations with robust programs and resources, our students can and will achieve at high levels,”  Bowser said in a statement.

Graduation rates are seen as an important measure of how well schools prepare students for college and career. Research has shown students with diplomas are more likely to be successful — even if they do not go on to college.

The rise in graduation rates comes as test scores in the District continue to improve, but fewer than one-third of students rated college- or career-ready last year. The gap between the graduation rate and test scores has concerned some experts, who worry the District is handing out diplomas to students who are not ready for postsecondary education or the workforce.

In D.C. Public Schools, black and Latino students also saw a boost in graduation rates — to 72 percent and 71 percent, respectively — but they still lag behind their white classmates by more than 10 points.

Meanwhile, the graduation rate for the 204 white students in the cohort tumbled nine points, to 83 percent. Antwan Wilson, chancellor of D.C. Public Schools, said some of these students may have transferred outside of the District and graduated on time. But if the school system is unable to verify that they enrolled at another school, they are counted as dropouts.

Wilson said the gains overall come from targeted efforts to boost achievement among students who struggle to reach graduation.

The district put college and career coaches in some high schools and directed them to focus on students at risk of not graduating.

The district also created ninth grade academies five years ago to help freshmen navigate the start of high school, a challenging time for many students that makes them particularly vulnerable to failure. These “schools within a school” isolated first-time ninth graders from older classmates, giving them more attention and support with the hopes of promoting more of them to 10th grade. Eight of the high schools with academies have seen huge gains over the last five years — H.D. Woodson High’s rate this year is 83 percent, 30 points better than it was in 2012.

Wilson highlighted gains made by the district’s comprehensive high schools –neighborhood schools that serve all students — which posted the largest increases but still lag far behind selective high schools, which require students to apply. Anacostia High saw a  17-point gain, boosting its graduation rate from 42 percent to 59 percent.

“Given the diverse needs and the diverse student bodies . . . I think it’s important to appreciate the effort of the faculty, the staff and the school leaders and the students and the families,” Wilson said.

Still, there are yawning gaps between the District’s best- and worst-performing schools. Wilson High, which serves more affluent students in the city’s Northwest, graduated 90 percent of students on time this year.

The nation’s graduation rate has been steadily rising since 2011, when states and the District adopted a uniform way of reporting the rates. About 83 percent of students nationwide graduated on-time in the 2014-2015 school year, according to the most recent data. Former President Barack Obama touted the rates when he highlighted his administration’s efforts to improve public school last year.

A previous version of this story incorrectly stated last year’s graduation rate at Anacostia High and the amount by which it improved this year. This story has been updated.