Oregon’s high school graduation rate improved by 2 percentage points for a second straight year, marking the most sustained improvement in a decade, the state reported Thursday.

Statewide, 79 percent of students in the class of 2018 earned diplomas within four years, the Oregon Department of Education said.

The gains were broadly shared, with Latinos, Native Americans, whites, low-income students, girls and boys all matching or exceeding the statewide rate of improvement. The improvement in the statewide rate meant 935 more students earned diplomas last spring than would have done so, had the rate held flat.

The most glaring exception to the otherwise rosy report was among black students, whose on-time graduation rate remained mired at 68 percent after showing steady gains the previous four years. The graduation rate among black students improved in Portland, but fell in Salem, Eugene, Gresham and other smaller districts.

State schools chief Colt Gill said the encouraging broad-based gains are a sign that strategies such as returning career-technical courses to the state’s high schools are paying off. Among students who took one or more such classes, 88 percent earned diplomas, he noted.

And he said the latest graduation rates are also a reminder that his agency and local educators need to keep fighting chronic absenteeism and pay more attention to minority, low-income and special education students.

Low-income students were 6 percentage points less likely to earn a diploma in four years than better-off students. And historically underserved minority students graduated at rates 7 percent lower than white students.

“We really need to keep an eye on equity-focused support,” Gill said.

It’s not yet known how Oregon’s new graduation rate stacks up against those in other states. Federal officials have yet to release state-by-state and national rates for the classes of 2017 or 2018. But for the class of 2016, Oregon’s 75 percent graduation rate ranked third-worst in the country. And one of the two states that performed worse -- Nevada -- outshined Oregon for the class of 2018. Nevada schools posted an 83 percent graduation rate for that group, according to the Nevada Department of Education .

UPDATE: The state-by-state rankings for the class of 2017 are now out:

Many of the Oregon districts that recorded the largest gains are on the coast, including Astoria (up 14 percentage points), Seaside (up 7) and Tillamook (up 8 percentage points to 84 percent).

In the metro area, seven districts, including Tigard-Tualatin, Reynolds and David Douglas, outpaced the statewide gain. Just two, Gresham-Barlow and Centennial, registered significant declines.

As it did last year, McMinnville High delivered a standout performance when it came to getting Latinos and other minority groups with historically poor school outcomes to graduate. In McMinnville’s class of 2018, 89 percent of those students earned a diploma in four years, the same rate as last year. Closer to Portland, Tualatin High and and Hillsboro’s Century High also delivered on that front, graduating 87 and 86 percent of their historically under-served minority students on time.

State officials believe hands-on career-related coursework in areas such as graphic design, automotive technology, computer programming and construction can help keep a segment of students otherwise bored by high school engaged and on track.

As a result, in 2012 the state began awarding career-tech “revitalization” grants of about $100,000 to $500,000 to a handful of high schools or high school consortiums each year to start or upgrade multiple-course career-tech pathways. It stepped up its outlays significantly to about $80 million a year starting last school year after voters overwhelmingly approved Measure 98, whose backers heavily promoted its promise to expand career-tech offerings.

Students in the class of 2018 who completed a three-course sequence in a career or technical field have the highest graduation rate of any group of students -- 93 percent -- except talented and gifted teens.

Despite the improvements, Oregon’s graduation rates for nearly every group of students remained well below national averages set by the class of 2016, the most recent class for which the U.S. Department of Education has released national and state-by-state figures.

Oregon trails the nation’s 2-year-old graduation rates most sharply for black students and for white students, who are both 8 percentage points less likely to graduate than their counterparts around the country. Oregon’s graduation rate among students who were still mastering English as a second language during high school also badly trails the national graduation rate for English learners set two years ago. Just 56 percent of Oregon’s ESL students earned diplomas in four years of high school last year, compared with 67 percent of English learners in the nationwide class of 2016.

-- Betsy Hammond

betsyhammond@oregonian.com