DES MOINES – If you live in the Midwest, chances are you’ve got a couple frozen pizzas at home, and probably a few more on your shopping list. You might even be chewing a mouthful of one right now.

The odds are good because the typical Midwesterner ate frozen pizza 22 times last year – a rate nearly double the national average of about 13 times a year, according to a study conducted by a New York market research firm.

What is with the Midwest and frozen pizza?

“It’s fast and convenient,” Holly Gilliland, a mother of four from West Des Moines, said recently while browsing frozen pizzas at Hy-Vee in West Des Moines. “It’s less expensive than ordering out.”

Maybe. But convenience only explains why frozen pizza has evolved into $2.4 billion national industry, not what makes Midwesterners love it so, said Andrew Smith, the editor of “The Oxford Companion to American Food and Drink.”

How do you explain that the typical Hy-Vee grocer – of which there are 220 in the Midwest – stocks more than 1,000 varieties of frozen pizza in more than 60 feet of freezer space, and always features a frozen pizza in its weekly sales?

“I have no idea why, but I think it’s the same pizza sold over the world,” said Mike Kueny, director of a Des Moines Hy-Vee.

Perhaps it’s the food’s local roots. After all, the Midwest did popularize the stuff.

Credit goes to Rose Totino, who, in 1951, opened a pizzeria in Minneapolis. The growing demand for frozen foods overall persuaded her that pizza needed a slice of the business, and in 1962 she launched the first popular national frozen pizza brand.

Dave Linn, vice president of the industry leading pizza division at Northfield, Ill.-based Kraft, buys that theory. So much so, the company even chose the Midwest last January for launching DiGiorno Ultimate, a premium pizza loaded with toppings.

“Without a doubt, frozen pizza consumption is more developed in the Midwest than anywhere else in the U.S.,” he said. “Frozen pizza has been around in the Midwest for about 45 years. It was really born in the Midwest.”

But pizza itself wasn’t born there, which Barb Stuckey thinks might explain the frozen pizza fascination. Stuckey is vice president of marketing for Foster City, Calif.-based Mattson, a food developer that has played a big role in the frozen pizza industry.

The East and West Coasts have strong pizza cultures, she said. New York was home to the first licensed American pizzeria and California’s innovative chefs (such as Wolfgang Puck) are credited with pushing pizza in new and exciting directions. “The Midwest was generally settled by immigrants from countries that didn’t make pizza, and they really didn’t develop their own style, with the exception of Chicago deep dish, which arguably is not a real pizza,” Stuckey said.

“Because of that, pizza in the restaurant segment is probably stronger on the coasts, and so people need to scratch that itch less frequently with frozen pizza,” she said.

Or there’s the fresh vs. frozen food theory. Historically, quality fresh foods haven’t been as readily available in the Midwest as on the coasts, said Diana McMillen, food editor at Midwest Living magazine.

The heartland of frozen pizza popularity consists of Iowa, Kansas, Minnesota, Missouri, Nebraska and North and South Dakota, according to the latest data from market research firm NPD Group.

Older data – a 1997 report from ACNielsen – refines that even further, pinpointing Des Moines as the epicenter.

New Englanders are the most likely to snub frozen pizza, indulging just over six times a year.

That might be because the Northeast takes pizza more seriously, demanding exotic toppings such as clams and potatoes, said Jane Stern, who with her husband, Michael, chronicles American food culture and local eateries at roadfood.com.

“I just don’t think it’s taken as seriously as it is in the East,” Stern said. “In the Midwest, it’s just kind of teenage food, or something you eat when you get the munchies to eat. It’s not like an art form like it is [on the East Coast].”

Phil Lempert, a grocery industry analyst who edits the Supermarket Guru Web site, suspects Americans probably eat about the same amount of pizza overall, regardless of where they live.

But the sheer volume of pizzerias and restaurants on the coasts makes frozen pizza less attractive in those regions.

“If you look at New York, for example, there’s a pizza place on every corner, so it’s unlikely that you would go buy a frozen pizza at Food Emporium, because you could get it fresh,” he said. “Not so in the Midwest.”

Perhaps the answer lies in a dearth of delivery in the heartland, said Ruth Litchfield, professor of food science.

“If you’ve got folks who are working in Des Moines and commuting in but live in a rural area next to that metropolitan area … they may be using frozen pizza because they don’t have delivery,” she said.

Even most locals are at a loss for a concrete answer. Joan Warren, manager of the pizzeria Great Plains Sauce & Dough Company, 129 Main St., said great fresh pizzas (including theirs, of course) are widely available.

Warren has “no idea” why people would prefer frozen pizza when there are so many pizza places around.

Lorna Davros does. She’s the assistant to the mayor and city council in Des Moines.

“That’s because we have great sales. Five pizzas for $10,” she said. “You take them home and doctor them up. You can’t beat that.”