In a time of natural disaster, the federal government uses a simple gauge to determine the toll Mother Nature has taken on a local area.

It's called the Waffle House test, which uses the operating conditions of the resilient Southern restaurants as a barometer for how well an area will recover from a hurricane, tornado or other hazard.

"The Waffle House test just doesn't tell us how quickly a business might rebound — it also tells how the larger community is faring," said a FEMA blog post from 2011, when Craig Fugate was administrator under former president Obama. "The sooner restaurants, grocery and corner stores, or banks can re-open, the sooner local economies will start generating revenue again — signaling a strong recovery for that community."

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Fugate said the system "came out of the '04 hurricanes," when he was Florida's emergency management director. Here's how Fugate described the test on a 2016 episode of NPR's comedy podcast Wait Wait... Don't Tell Me:

"They are open most of the time. And that was the index. If a Waffle House is closed because there's a disaster, it's bad. We call it red. If they're open but have a limited menu, that's yellow," he said. "If they're green, we're good, keep going. You haven't found the bad stuff yet."

A few days after Hurricane Harvey ravaged the eastern coast of Texas, many Waffle Houses remained open.

Follow Sean Rossman on Twitter: @SeanRossman