According to the other national newspaper of record, 65 percent of Idaho adults reported creating or performing some kind of artwork in 2014—"artwork" being defined as making pottery, ballet dancing, painting pictures, writing creatively, etc. The national average was 45 percent.
More interesting than Idaho's artsy bent is the general geographic trend of creativity. Data from the National Endowment for the Arts show "America's Great Creative Divide" isn't from coast to coast, but North to South.
In no state south of 36°30'—which WaPo points out coincides with the parallel that marked the new slave states from the free states in the Missouri Compromise—did a majority of people report engaging in artistic activity.
The reason? NEA's analysis suggested a combination of high rates of poverty and low educational attainment, which tend to feed each other. That still doesn't explain why Idaho ranked so high, considering its headline-grabbing number of minimum wage jobs and famously poor performing education system. Maybe we're not so poor and dumb after all.