When Palo Alto mail carriers complete their appointed rounds Saturday, their trucks could be more full than when they started out in the morning.

At least, that's if residents cooperate.

Saturday, May 10, is the Stamp Out Hunger Food Drive, the National Association of Letter Carriers' annual effort to replenish local food banks.

The group is asking postal customers to place shopping bags full of canned and other nonperishable foods by their mailboxes, and their postal carriers will pick up the bags Saturday when they deliver the mail.

Last year, letter carriers in Santa Clara County collected 145,059 pounds for local agencies that address hunger, the Second Harvest Food Bank reported.

This year, all letter carriers on Palo Alto's 92 delivery routes are expected to take part, according to Palo Alto Postmaster Dean Maeda.

"Some even come in on their own time," he said.

The event is the nation's largest single-day food drive, extending to 10,000 cities and towns, according to the letter carriers' group. Last year, more than 74 million pounds of food were donated, which fed an estimated 30 million people.

About one in six Americans live with the uncertainty of where their next meal will come from, the group states.

By nature of their work, the mail carriers often know the people on their routes and the conditions they live in, said Frank Ware, president of the Peninsula and South Bay carriers' branch, local 1427.

"There are people who can't get by with what they're making. They have two jobs and such. They have kids. The rents are exorbitant," he said. "They rely on the food bank to replenish their supplies."

The drive is especially important as summer approaches, with federally funded school-lunch programs stopping and donations from last year's holiday season running out, the press release states.

"It's the time of year when the food banks dry up," Maeda said. "It's a good time to get them stocked so they can get food to the people who need it."

The carriers are encouraging people to donate canned soup, canned vegetables, canned meats and fish, pasta, peanut butter, rice or cereal in sturdy bags.

"We just ask people to leave as much food as they can," Ware said.

The drive has been going on for 22 years and has the support of the United States Postal Service as well as numerous local nonprofit organizations and businesses.

"Getting a federal agency to allow us to do this, it's a miracle," Ware said, noting that, among other things, the letter carriers use space at postal branches to organize donations before delivering them to the food banks. "It does cost the agency a sum of money."