By Lou Carlozo, dealnews contributor We're not sure what incantation St. Patrick uttered when he supposedly drove the snakes out of Ireland. But we're sure it had nothing to do with green beer, corned beef, or dying the Chicago River the color of clover in spring. In fact, St. Patrick himself — in his own words! — dedicated his life to being "an instrument whereby multitudes who had worshiped idols and unclean things had become the people of God." Hmmmm. And come March 17, countless people will drink to that, again and again and again and.... St. Patrick's Day shall soon be upon us. It's a time for counting the copious consumption of all things Irish, semi-Irish, or not even remotely Irish. And the consumer forecast this St. Patrick's Day calls for more than 133 million celebrants to take part in the action, according to the National Retail Federation. St. Patty's spending should grow to a whopping $4.7 billion, a figure equal to 2% of Ireland's GDP for an entire year. Begorrah! So whether you're a red-headed laddie from County Cork, or a non-Irish bystander who simply looks smashing in green, here's the rundown on stats, spending, and trivia surrounding this mid-March holiday. Read on, and shout "Erin go bragh" as often as the spirit moves you. Overall St. Patrick's Day Spending: $35.27 Per Person That National Retail Foundation estimate of almost $40 a head might sound low compared to, say, Christmas or Valentine's Day. But consider that St. Patrick's Day is both a non gift-giving holiday (unless you're buying the first round) and one where stats are compiled for those 18 and over — with alcohol consumption taking place (we hope) among those 21 and over. Folks will spend on items such as green attire, décor for their home and office, and festive food and drinks. As for the attire part, we're not sure what the St. Pat's equivalent of the Ugly Christmas Sweater is, but we imagine something with a spangly leprechaun and way, way too many clovers. Or better yet, check out these Ugly St. Patrick's Day Sweaters on Pinterest. Celebrants Expected to Wear Green: More Than 8 Out of 10 The NRF estimates don't break down how the Irish and honorary Irish will don the green, but the choices are limitless, from "Kiss me, I'm Irish" pins to striped scarves, Irish-themed "Cat in the Hat" headgear, and the aforementioned nauseating green sweaters. But it doesn't stop there: a quick trawl online reveals St. Patty's knee socks, striped arm warmers, green Santa suits, and jumbo leprechaun heads that fit over your noggin and torso to give you the appearance of a wee sprite. So what will yours truly wear? At the very least, I'll don my green-and-white Chicago Cubs hat with a shamrock on it, all to honor a very unusual St. Patty's ritual. Which is... Dye Used to Turn the Chicago River Green: 40 Pounds In one of the Midwest's more bizarre St. Pat's traditions, members of Chicago's Journeymen Plumbers Union pour about 40 pounds of dye into the Chicago River, turning it an emerald green. The practice dates to 1961, when one Stephen Bailey discovered that a dye used to detect pollution leaks into the river had stained a plumber's white overalls the color of a leprechaun's bowler. And so a yearly rite of river recoloring was born, but one that makes long-time Chicagoans roll their eyes since the Chicago River is already green the other 364 days of the year. (OK, so it's a more of a jade color, whereas this dye looks more the Fighting Irish hue.) Number of American St. Patrick's Day Parades Dating Back to the 1700s: 3 Chicago's celebratory parade only dates to 1837, so we have a long way to go in terms of being old-timey, as three of America's best parades date back to colonial times. Boston (of course) got things started in 1737, followed by New York (1762) and Philadelphia (1780). So remarkably, Boston's parade was already 43 years old when Philly's got started, while the Declaration of Independence was less than four years old. About 150,000 marchers will take part in New York's parade, and while we have no tally on how many portable toilets will line America's marching routes, we know some will have cute Irish names like "LepreCAN Portable Restrooms" (as seen in Chicago). Shortest St. Patrick's Day's Parade: 98 Feet You probably won't see any porta-potties lining the parade route in Hot Springs, AR, which is gearing up for its "First Ever 10th Annual World's Shortest St. Patrick's Day Parade." The entire parade route is less than 33 yards, and runs along Bridge Street, one of the world's shortest streets. But it's long on fun, as the Grand Marshals this year (returning, no less) are Bo Derek (of 10 fame) and John Corbett (Northern Exposure, My Big Fat Greek Wedding). The Total Beer Tab: More Than $245 Million By all accounts, a bar or liquor store that's well stocked can make 1% of its total annual sales on St. Patrick's Day alone. Our friends at The Motley Fool estimated that last year, brewers took in $245 million in St. Patrick's Day sales, using figures compiled by IbisWorld. That's bound to go up this year, though there's no reliable estimate we could find in terms of how much of that beer will be dyed green. On the other hand, advice abounds on everything from how to cure a green beer hangover to whether you might see that dye reappear on a trip to the bathroom. Speaking to the former point (and definitely not the latter), here are some green beer hangover tips from no less a venerable source than the International Business Times. The article also features a photo of President Barack Obama hoisting a pint, and as we all know, O'Bama is a lovely Irish name. Guinness for the Record Books: About 13.7 Million Pints On any given day, about 5.5 million pints of Guinness are raised across the globe in toasts of all kinds. But come St. Patrick's Day, that number more than doubles, according to BBC News. In 2011, that number was pegged at about 13 million pints, and we can only expect it to grow in 2013 — a modest 5% rise from 2011 would put the number at about 13.7 million pints. So will the 2013 tally make the Guinness Book of World Records? We're not sure, but we'll drink to that. Any excuse to celebrate the end of winter deserves a night out on the town. That said, there's another poignant number that puts the holiday in perspective. An estimated 5.5 million people will visit St. Patrick's cathedral in New York City. There they'll honor the legacy of a Catholic saint who changed the course of a nation. Ireland has given the world abundant poetry, music, wit, and literature. Whether you say a blessing, hoist a pint, or do both, we hope you keep Patrick in mind as you celebrate the holiday bearing his name. Front page photo credit: BMI Karts Photo credits top to bottom: Fashionably Geek, Party City, Robin Silvergate, Christian Science Monitor, and M-Hole Mommy Related dealnews Features: The Best and Worst Things to Buy in March How to Save on Any Online Order, from Groceries to Overweight Items Poor Sales and Too Much Stock Mean It's the Best Time Ever to Buy UGGs Lou Carlozo is a dealnews contributing writer. He covers personal finance for Reuters Wealth. Prior to that he was the managing editor of WalletPop.com, and a veteran columnist at the Chicago Tribune. Follow @dealnews on Twitter for the latest roundups, price trend info, and stories. You can also sign up for an email alert for all dealnews features.