A map shows which counties in California have the highest percentage of high school dropouts.

To determine which counties had the highest percentage of dropouts, Newsweek analyzed the latest data from the U.S. Census Bureau which tracked the number of residents 25 and over with at least a high school diploma.

The analysis found that Monterey County had the highest percentage of high school dropouts, at 27.3 percent.

That was followed by Colusa County with 26.7 percent, Madera County with 26.4 percent and Merced County with 25.7 percent. Imperial County has 25.5 percent.

The counties with the highest number of high school graduates were all in northern California. Placer County had the lowest dropout rate, with just 4.4 percent. Other counties—including Trinity, Nevada, Shasta and Plumas—all had fewer than 6 percent.

Newsweek previously reported that California, the nation’s most populous state, ranks at the very bottom of U.S. states when it comes to the number of high school diploma holders. Just 84.7 percent of California residents aged 25 or over have graduated from high school, according to 2022 Census data.

However, the latest data from the California Department of Education has shown that students are graduating from high school at higher levels than before the COVID-19 pandemic.

The graduation rate for the class of 2023 was 86.2 percent—down about a percentage point from the previous year, but still higher than pre-pandemic levels.

The data was “encouraging,” State Superintendent of Public Instruction Tony Thurmond said in December, but “our work is not complete.”

“We have made an unprecedented investment in services that address the needs of the whole child,” Thurmond said. “We can see that those efforts are paying off, but this is only the beginning. We need to continue providing students with the tools they need to excel, especially now that we are successfully reengaging our students and families, so we can close gaps in achievement in the same way that we have begun to close the equity gaps in attendance and absenteeism.”

Students across the country have been absent at record rates since schools reopened during the COVID-19 pandemic, adding further challenges as schools work to help students recover from huge learning setbacks.

Those who end up dropping out of high school could face adverse consequences well into adulthood, according to Jennifer Lansford, a research professor of public policy at the Sanford School of Public Policy at Duke University.

“The long-term consequences of dropping out of high school can be very negative for individuals who drop out, their families, and society as a whole,” Lansford told Newsweek.

She pointed to research that she and colleagues carried out using data from children that were followed from the age of 5 until 27.

That research found that individuals who dropped out of high school were nearly four times more likely to be receiving government assistance, were twice as likely to have been fired two or more times, and were more than three times more likely to have been arrested since the age of 18.