EXPLAINER: To prevent wildfires, the entire state’s power grid is subject to planned blackouts.

As with most vicious problems, the roots of the state’s power dilemma go back decades. For starters, the state is fire prone. “It’s a place that nature built to burn,” writes fire historian and Arizona State University professor Stephen J. Pyne. Almost all the region’s precipitation falls during the winter. By early summer, the hills are stocked with fuel and tinder-dry. And California’s federal and state lands are chronically undermanaged when it comes to controlled burns and reducing fuel loads. (President Trump evoked chuckles when, visiting the Camp Fire site, he described Finland’s superior forest management practices as “raking and cleaning.” Though inelegantly expressed, his recommendations reflected those of many wildfire experts.)

Then California’s ferocious winds, especially in late summer and fall, disrupt the usual flow of air off the Pacific: huge rivers of hot, bone-dry air from the state’s deserts and mountains rush unstoppably toward the coast. Known as the Santa Ana winds, the gusts can roar at 40 miles per hour or more for days at a time. Imagine a smoldering cigarette butt sitting on a pile of crumpled newspaper and being blasted by a hair drier—for hours on end—and you start to appreciate the havoc a single ember can wreak on the desiccated California landscape.

A wildfire that passes through uninhabited forests and grasslands doesn’t do much permanent damage. In fact, these ecosystems have evolved to benefit from occasional fires. In recent decades, though, California’s wild areas have filled up with people. (Though the media portrayed Paradise as a small town, the mountain community was actually home to 27,000 people. That’s roughly the population of New London, Connecticut) Even big cities bump up against wild country, with subdivisions filling mountain canyons and advancing into brushy deserts. Fire experts call these zones the “wildland-urban interface.” Nearly a third of California homes are built in these hard-to-protect areas.

Many California residents—especially retirees—are drawn to rural areas by the natural beauty. Who wouldn’t want to live in the Sierra foothills? But many also move to escape soaring housing costs in the state’s notoriously anti-development major cities.

And now the people smart enough to leave the cities are having their power switched off. It’s almost like California wants to be rid of smart people.