Thanksgiving's almost upon us. And, seeing as how millions of turkeys are about to get plopped on dinner tables across the country this Thursday, the least we can do is give them their own wonky chart.

So here's a graph from a surprisingly fascinating 2007 U.S. Department of Agriculture overview (pdf) on the turkey industry. It shows that turkeys in the United States have been getting steadily fatter in the past two decades, even as the overall number of turkeys raised and slaughtered has been declining:

In 1986, the average turkey weighed 20 pounds. By 2006, that had risen to 28.2 pounds per bird. Why's that? Because turkey farming has become a complex industrial operation that has seen big productivity gains. Here's the USDA report:

Turkeys were historically hatched and raised on the same operation and either slaughtered on or close to where they were raised. Historically, operations owned the parent stock of the turkeys they raised supplying their own eggs. The increase in technology and mastery of turkey breeding has led to highly specialized operations. Each production process of the turkey industry is now mainly represented by various specialized operations.
Eggs are produced at laying facilities, some of which have had the same genetic turkey breed for more than a century. Eggs are immediately shipped to hatcheries and set in incubators. Once the poults are hatched, they are then typically shipped to a brooder barn. As poults mature, they are moved to growout facilities until they reach slaughter weight. Some operations use the same building for the entire growout process of turkeys. Once the turkeys reach slaughter weight, they are shipped to slaughter facilities and processed for meat products or sold as whole birds.

"Turkeys have been carefully bred to become the efficient meat producers they are today," the report concludes. "The increase in bird weight reflects an efficiency gain for growers of about 41 percent." It also means that fewer turkeys get slaughtered for more and more meat.

Of course, there are also a few not-so-savory downsides to hyper-efficient industrial turkey farming. As Lynne Peeples reported last year, tens of millions of turkeys in dense factory farms are fed a diet that includes low doses of antibiotics, which help animals grow faster for still-mysterious reasons. Public-health experts worry that these crowded farms could, in turn, help spread new strains of antibiotic-resistant bacteria.

In any case, for more on the economics of the turkey industry, see Tim Taylor's post. And Matt Yglesias explains why turkeys counterintuitively get cheaper during Thanksgiving. If we missed any good bits of turkey wonkery, let us know.

Update: Commenters point out that being fattened so unnaturally can be a pretty miserable experience for the turkeys themselves. There's a not-so-appetizing description in this report (pdf) from the Humane Society.