When volunteers open the doors at the Arlington Food Assistance Center these fall mornings, people are always waiting.

They are young and older, white, black, Hispanic, Asian and all of the other ethnicities found in the increasingly diverse county. Some have children in tow; others grasp only the handles of their reusable grocery bags. Some have familiar faces, but many waiting quietly in line are new clients, and there are more and more of them.

During the second week of September, 1,572 families went to the warehouse just off Four Mile Run in Shirlington for eggs, milk, frozen chicken, pastries and produce. That was an all-time record for the 24-year-old food bank — but it lasted only until the last week of September, when 1,602 families (4,050 individuals) were served.

“We’ve been increasing throughout the summer at the rate of 10 to 15 families a month, and lately we’ve seen a real spike,” said Charles Meng, the food bank’s executive director. “The people are the still unemployed or recently laid off and those we consider to be underemployed, [because] $7.25 an hour is not a living wage in Arlington County.”

As the nation struggles with tenacious economic problems, Arlington County has one of the lowest unemployment rates in the United States, just below 4 percent. Half of the county’s residents make more than $102,384 annually, and the per-capita income is $74,035. Many residents are highly educated, and in August, a national magazine called Arlington one of the best spots in the country to be rich and single.

That’s undoubtedly true, but none of the clients in the waiting room carried CNN Money magazine with them. What they had were worn jackets, strollers with wobbly wheels and the precious paper ticket that gave them entry to the warehouse of food.

Robert Arnez turned up at the food bank one morning last week and took one of the plastic chairs in the waiting room, not far from a volunteer who was turning donated apples into applesauce in an electric skillet while several children watched hungrily. He sat with a laid-off plumber, a woman whose hours were cut at the dental office where she works, a mechanic, a homeless newspaper vendor and a former Dulles Airport security guard who’s on disability.

“I had a job,” Arnez said. “Until six months ago, I worked construction. Then — no work.”

He still finds work one or two days a week, but that’s not enough to keep milk and bread in the home, not if he wants to keep up with the rent and pay for transportation and clothing and the other expenses that he, his wife and two children incur.

“This helps me keep my car,” said Margie Lugo, who has used the food bank off and on for seven years. A retired nursing assistant who drives her used car twice a week to get to medical appointments, Lugo appreciates that the food bank stocks the basic food groups.

She has noticed the increase in demand this summer. “There’s a lot more,” she said. “I thank God we have this.”

“I come here because I can’t get food stamps because I make too much,” said Donald James of Arlington. “How can I make too much money when all my money goes to rent and utilities?”

Friends Amira Mahammed and Nissreen Bellal brought their well-behaved children with them and quietly waited in a corner to pick up whatever they could get. They mostly wanted bread. “I have a big family — four children and a husband — and we need a lot of bread,” Mahammed said.

The food bank serves all people the first time they show up. For subsequent visits, people are asked to get referrals from Arlington’s Department of Human Services. Some are undocumented immigrants, but the food bank doesn’t ask for green cards or proof of citizenship. It also distributes food at four of the five low-income senior centers in the county and is about to resume its “backpack” program at schools, which give students who are homeless a backpack stuffed with food for weekends and other holidays when subsidized breakfasts and lunches are unavailable.

“Thankfully, we’ve been able to meet demand, and I expect to be able to continue to meet that demand,” Meng said. “We’ve got tremendous community support. . . . We just received 2,203 boxes of cereal from the taekwondo schools, which is a tremendous help. . . . Churches are still strong supporters . . . a race over the weekend had leftover bottles of water, which they brought in.”

What worries Meng most is that he used to be able to predict when demand would increase. Cupboards would empty during the last week of the month, as food stamps, support checks and paychecks ran out. But the first few days of October are seeing a surge in demand, and it’s well ahead of the holiday season.

“This doesn’t bode well for the rest of the month,” he said.