No law says that you have to have turkey on Thanksgiving, but just try to imagine the holiday without it.
The Jackson family from Denver doesn't have to imagine.
"Last year, we had pork chops because that's the only thing we had," Tina Jackson said.
The family of five has struggled ever since Tina Jackson's husband, Ken Jackson, was laid off from his shipping and receiving job a few months ago. This year, they asked their church for help.
The Jacksons' church and other community organizations that typically have been a refuge for families down on their luck during the holidays are struggling too.
With less than a week before Thanksgiving, today the Association of Gospel Rescue Missions surveyed 25 of its members in some of the country's biggest cities.
The association found that more than half of those missions -- including ones in Los Angeles, Chicago, Houston, Dallas, Phoenix, Detroit and Seattle -- have seen a "major drop" in turkey donations this year.
The missions "will not be able to provide food boxes the way they have done in the past unless there is a sudden increase in turkey donations in the next couple of days," association president John Ashmen told ABC News.
On a busy downtown street in Denver, Scott Croft and a team of volunteers from the Denver Rescue Mission have been eagerly standing by, waiting for the seasonal stream of drivers who usually pull over this time of year to unload thousands of donated frozen turkeys.
"We've gotten kind of a slow start," said Croft, pacing the side of the road wearing a bright yellow safety vest.
This year, they've done a lot of waiting.
"We started our turkey drive on Nov. 1," said Greta Walker from the Denver Rescue Mission. "Our goal was to get at least 6,000 turkeys. We realized on Nov. 10 that we had zero turkeys in our freezer."
The struggle in Denver is playing out in towns across the country.
In Bridgeport, Conn., charities have met only half of their goal and are still 1,000 turkeys short.
Down south in Atlanta, big corporate donors haven't come back. Donations are down 38 percent.
Out West in Cabazon, Calif., charities have launched a backup plan. They're giving out 10-pound chickens.
Down the road in Compton, Calif., the Salvation Army has 500 requests for turkeys, but all that sits in its ice cold freezer is one lone turkey.
"People just keep applying, and because we don't have the food that we can supply we have to turn them down," said Capt. Ezekiel Guevara of Compton's Salvation Army.
Patricia Torres, a single mom of two, was one of them.
"We take it day by day, you know...I just keep going out looking for a job and you know... my kids they ask me for so much stuff ...I tell them,'ok, later,'" Torres said.
Charities blame their empty freezers on the poor economy and higher turkey prices.
"Retail prices will be up, on average, about 20 percent this year," said Thomas Elam of Indiana-based FarmEcon, an agricultural industry consulting firm.
Elam blamed rising costs on a reduction in turkey supply and production this year, along with a steep jump in the price of corn and soybeans farmers feed growing birds. Now, higher prices at the supermarket may be causing fewer people to buy an extra turkey to donate.