Everything looked normal at the Pentagon this morning.

The 17-and-a-half miles of corridors were bustling with workers — military and civilian — who appeared to be going about business as usual.

But thousands of civilians were just there to fill out paperwork, set an away message on their email, and wave goodbye to their uniformed co-workers.

Welcome to the federal government shutdown of 2018.

“The local bars should be doing a brisk business this afternoon,” wisecracked one furloughed Pentagon worker, who was sneaking a smoke around the corner from the Pentagon’s main River Entrance.

The mood was generally one of resignation, tinged with frustration, and sprinkled with occasional gallows humor.

“This might be fun if it was the first time,” said one worker. “But we’ve seen this movie before.”

Another civilian worker bristled at a well-meaning “enjoy your vacation” wish.

“This is not a vacation,” she said through gritted teeth.

Even though workers knew they were being furloughed today, they still had to come in to sign their documents in person, leading one DoD employee to grumble: “Everything else we can do electronically, but this we have to do face-to-face.”

In another office, a military supervisor was busily signing papers canceling travel for a group of reservists, who were supposed to be visiting the Pentagon.

“It’s just a nuisance,” he said.

The Defense Department employs some 750,000 civilian workers around the world, about 24,000 at the Pentagon, and estimates roughly half of that workforce is being furloughed. It ends when Congress restores funding for the federal government.

“I’ve got 23 people, and 12 are being sent home,” said Col. Rob Manning, director of Press Operations. Only two civilians were deemed essential.

Among them was Dana White, chief spokesperson for the Pentagon.

Defense Secretary Jim Mattis is traveling today, and his trip to U.S. Pacific Command in Hawaii, Vietnam, and Indonesia is considered an essential “national security” mission.

By mid-morning, the Pentagon was beginning to look a little emptier, as thousands of civilians began to head for the exits.

At noon a check of popular eating spots showed the Pentagon was hardly deserted, with what appeared to close to the usual lunchtime crowds and plenty of civilian suits among the camouflage.

There was a long line at the CVS drug store, and dozens of people were enjoying the mild temperatures in the Pentagon’s five-acre center courtyard.

And by afternoon, the depleted staffing levels at the Pentagon will gave new life to an old joke.

“How many people work at the Pentagon?”

“About half of them.”