LOS ANGELES -- Lisa DiMarzio and her younger sister sorted through racks of unusual Valentine's Day greeting cards at a Card Factory store here.

"I used to be real big on teddy bears," DiMarzio said.

"I think they're baby-fied," volunteered her sister, Andrea Capoziello.

Mostly they picked up cards with lots of hearts on them. Both said they still had stacks of cards at home that had struck their fancy on previous visits, but they were back to find just the right sentiment for the right friends and relatives.

Americans will exchange nearly a billion cards by Sunday, half of them by hand, according to the Washington-based Greeting Card Association. Only Christmas, with 2.2 billion cards, provides card makers with a greater annual bonanza than February's $280 million lovefest. Popular cards this year range from the romantic to the risque, and take longer to design and distribute than most buyers realize.

Teachers are the leading recipients of Valentine cards, followed by children, mothers, wives and sweethearts, Greeting Card Association spokeswoman Patti Brickman said. Schoolchildren buy small, cheap cards by the box, and exchange an average of 22 cards apiece each year, she added. "That goes along with teachers receiving a lot of them."

Some of this year's commercially sold cards may be treasured for years, while others are crumpled immediately and thrown straight in the trash can.

But all these cards take months to design, produce and distribute. At Cleveland-based American Greetings, the nation's second-largest card maker after Hallmark Cards, 500 artists, writers and editors work to develop cards that may take as long as 18 months to reach the consumer, spokeswoman Jody Roberts said. About 90 percent of the designs are changed each year, although some of the new cards contain one-liners or artwork from best sellers of past years, assistant product manager Leslie Croy said.

Creative Papers Greeting Cards -- a division of Norwalk, Conn.-based C.R. Gibson -- starts making Valentine art assignments to free-lance writers and artists as early as March, product manager John Carroll said. Finished copy is not ready until May, June, or even early July.

Typesetting and other preparations for printing take a week to a month, and the cards are printed in July and August. Samples and catalogues go out in late August and September, and orders from stores are taken through late January, Carroll said.

Creative Papers starts shipping Valentine cards on Dec. 1 to the warehouses of major chains. But small, independent gift shops with little storage space often ask not to receive their shipments until after Christmas, Carroll said. Greeting cards for Easter, Mother's Day, Father's Day and graduation are drawn and printed at the same time as Valentine cards, but are not shipped until February.

A wholesale carton of Creative Papers' cards holds a dozen copies each of 16 different designs, for a total of 192 cards. The cards sell in stores for 95 cents apiece, so a carton is worth $182.40 at retail. The company charges retailers $91.20 a carton, Carroll said. "Their markup is 100 percent."

Most larger card companies allow retailers to return or destroy unsold cards and receive credit or special discounts on future purchases, Carroll said. "It's almost never cash back. It's credit against future purchases."

Children in school usually make Valentine cards in the shape of hearts. Yet commercially made Valentine's day cards are almost invariably rectangular. The reason, Carroll explained, is not a conspiracy among card makers or even difficulties in production and packaging. Rather, the problem lies in how store racks display cards.

"If you stand them on a point, they're going to fall over," he said.