Marijuana use in electronic cigarettes increased among U.S. middle and high school students from 2017 to 2018. This observational study analyzed responses from 38,000 students in the sixth to 12th grades on the National Youth Tobacco Survey. Researchers report that among all students, the proportion who reported ever using marijuana in an e-cigarette increased from 11.1% in 2017 to 14.7% in 2018, with the increases seen among some demographic groups, including male and female students, adolescents 13 to 17, high-schoolers, and non-Hispanic white and Hispanic students. [...]