Love is in the air...as well as in most retail stores from downtown Northville to the mega malls.

Today’s Valentine’s Day celebration marks one of the biggest sales days of the year for rose growers and florists, confectioners, jewelers and greeting card companies.

According to the National Retail Federation, Americans are expected to spend a staggering $18 billion on Valentine’s Day this year. Consider these numbers:

• 110 million roses (the majority being red) are expected to be sold in the three-days around today’s celebration, according to the Society of American Florists. Valentine’s Day is the No. 1 holiday for florists.

• More than 36 million heart-shaped boxes of chocolate are expected to be sold for Valentine’s Day, according to the Chocolate Manufacturers Association. Consumers are expected to purchase in total 58 million pounds of chocolate for Valentine’s Day bringing in $345 million in sales. Valentine’s Day is the fourth biggest holiday of the year after Halloween, Easter and Christmas.

• Jewelry spending is expected to reach over $4 billion this Valentine’s Day, according to the National Retail Federation. That’s a lot of bling.

• An estimated 150 million greeting cards are expected to be purchased for Valentine’s Day in the United States. This does not include children’s packaged valentines for classroom exchanges. Valentine’s Day is the second largest holiday for greeting cards behind Christmas. It comes as no surprise that teachers receive the most valentines of all recipients.

The staying power of valentine greeting cards in the age of electronic mail (and yes, e-card deliveries are on the rise) is testament to the tradition of greeting cards, and perhaps the sentiment.

While Americans exchanged hand-made valentines in the 1700s, mass-produced valentines did not make their debut until the 1840s when Esther A. Howland of Worcester, Massachusetts, established the first cottage industry for valentine card production.

In 1847, Howland, then 19, received an ornately designed English valentine. Believing the idea could catch on in the United States, she convinced her father, who owned the largest book and stationary shop in Worcester, to order her supplies of imported paper lace and floral decorations.

She set about making dozens of sample Valentine’s Day cards to add to her salesman brother’s inventory. She hoped to generate $200 in sale orders, and was stunned when her brother returned with $5,000 in advance orders. With orders exceeding her ability to create the cards alone, Howland recruited friends and established an assembly-line production for her new business. Two years later, she founded the  New England Valentine Company. She is credited with popularizing the lace Valentine and making Valentine cards a major American industry.

The “mother of the American valentine,” Howland sold her company in 1888 to her competitor George C. Whitney. Distinguished by their intricate detail, Howland valentines are prized today by collectors of antique papers and ephemera.

Howland’s valentines would prove the precursor to the mass-produced valentines that flourished during the Victorian era, and continue today. Several Victorian valentines are housed in the Archives of the Northville Historical Society.

Another Valentine’s Day tradition with deep American roots is the Sweethearts Conversation Hearts produced by the New England Confectionary Company (NECCO).

According to the company, it was Daniel Chase, brother of NECCO founder Oliver Chase, who first began printing sayings on candy in the 1860s. Today’s Conversation Hearts date to 1902, when the company also produced other shapes such as baseballs, watches and horseshoes.

In the last few years, the company has instituted all new phrases, flavors and textures. It produces a staggering 8 billion hearts each year. Production begins in late February and continues through mid-January of the following year. The company produces about 100,000 pounds a day of hearts...and sells out in just six weeks.

Sweet!