The District’s high school graduation rate ticked up to 64 percent in 2013, a three-point gain over the previous year, according to data that city officials quietly released last week.

But the city average — long among the lowest in the country — masks wide gaps between different groups of students and different schools, with charter schools and the school system’s selective high schools posting higher rates than traditional neighborhood schools.

Among charter schools, 79 percent of students graduated on time, an increase of two points over 2012. Meanwhile, just 58 percent of D.C. Public Schools students graduated on time, also an increase of two points. Citywide, 61 percent of students graduated on time in 2012.

“We’ve only just started to focus on strategies that will move our graduation rate, so we’re not surprised it hasn’t moved more quickly,” Chancellor Kaya Henderson said in a statement. “While we’re pleased the number is inching up and any progress is good, the real investments in high schools have only just begun. In the next two to three years, we expect to see much greater movement.”

In the traditional school system, on-time graduation rates ranged from 38 percent at Cardozo, a neighborhood high school in Columbia Heights, to 100 percent at Banneker, an application-only school just a few blocks away from Cardozo.

Across the school system, 55 percent of black students and 53 percent of low-income students graduated on time, compared with 87 percent of white students. Only 39 percent of students with disabilities graduated on time.

Only nine white students graduated from charter schools in 2013, and their graduation rate (75 percent) was lower than the graduation rate of black students (79 percent). But other gaps persisted in charters: Only 59 percent of students with disabilities and 29 percent of English-language learners graduated on time, for example.

The charter school with the best graduation rate was Washington Latin, where 95 percent of students graduated on time. Two schools east of the Anacostia River — Friendship Collegiate Academy, which graduated five times as many students as Latin, and KIPP DC College Preparatory — also posted graduation rates of 95 percent.

In both D.C. school sectors, there was a clear gender gap. Citywide, 70 percent of females and only 57 percent of males graduated on time. David Catania (I-At Large), D.C. Council Education Committee chairman and possible mayoral candidate, highlighted that difference Friday on WAMU-FM’s “The Kojo Nnamdi Show” and said it should raise questions for policymakers about what can be done to increase the success rate among males.

The graduation rates are calculated according to a federally mandated formula: The number of students who graduated in 2013 are divided by the number of students who were expected to graduate because they were ninth-graders four years ago, with adjustments for students who transferred in or out.

Of those students who did not graduate on time, about one-third were still enrolled in a D.C. public school, suggesting that they might graduate.

Advocates for neighborhood high schools have long argued that those schools tend to have lower graduation rates in part because they are legally obligated to serve all comers, which means they end up taking in challenging students who have transferred out of — or been kicked out of — selective and charter schools.

A list of each D.C. high school’s graduation rate is available online at www.osse.dc.gov. There is also a comparison of different subgroups of students and how the fared on the site.