Across the nation, Halloween has grown from a one-day celebration into an entire season.

Americans love Halloween so much, it's almost scary what they'll spend this year — an estimated $3.29 billion, up 5.4 percent from $3.12 billion in 2004. That's the most since the National Retail Federation began tracking Halloween spending in 2001.

In addition to outfitting themselves, nearly half of consumers will decorate their homes or yards, the federation says.

Department and discount stores have had Halloween greeting cards and decorations on the shelves for weeks. Halloween specialty stores started opening as early as midsummer.

Some say the allure is simple. "It doesn't involve much else," says Curtis Sigretto, owner of the Owenton, Ky.-based Halloween Express chain. "You don't have to get together with your family, you're not obligated to buy gifts. It's really just for your own personal enjoyment."

This year, much of the spending increase is expected to come from young adults.

For the past three years, Disney Stores have put out their Halloween costumes — think princesses and Power Rangers — in mid-July, although September and October are still the biggest costume-shopping months, says a merchandising manager.

With war and natural disasters dominating world news, costume shop owner Joy Galbraith wonders if people are thinking, "I've just got to escape."

Halloween greeting cards also have become a booming business. Up With Paper, the world's leading maker of pop-up greeting cards, first made Halloween cards last year. The company doubled the number it produced this year, and the cards now make up more than 5 percent of the company's business.

Three of the 12 card designs already have sold out, company president George White says.

Hallmark has expanded its Halloween product line by 25 percent over last year, spokeswoman Deidre Parkes says.

The Hallmark products, including 320 cards and a new line of ghost-town miniatures, began appearing in stores in early September, rather than late September as they did about five years ago, she says.

Cleveland-based American Greetings expands the number of its Halloween card designs every year, spokeswoman Amanda Todorovich says.

"More than ever, people just want a day and an occasion to have fun," she says. "That's why we think people are gravitating toward the holiday."