The USA may be a relatively young nation, but it has no shortage of ingrained eccentricities that puzzle the foreign visitor. From backwards date formats to tricky tipping etiquette, here's 32 quirks that the rest of the world struggle to understand.

Click through the gallery to find out 32 ways the United States does things differently...

Tipping can be a minefield in the States. While most travellers are used to adding 10% to a restaurant bill, in the US, almost anyone who provides a service expects a tip. Servers in restaurants will be offended by a tip of less than 18% because tips make up part of their minimum wage. Card machines often offer automatic tip options of 20%, 22% or 25%. Hotel porters will expect $5 to show you around your room, plus a dollar per bag, while bartenders expect at least a dollar for every beer poured and much more for a cocktail. Cab and delivery drivers expect a minimum of 15% too.

The whopping portion sizes available across the US are baffling to most foreigners. Fast-food giant McDonald’s phased out its 'supersize option' (which inspired cult documentary Supersize Me) in 2004 – but venues like Las Vegas’ Heart Attack Grill still peddle huge portions served by waiting staff dressed as nurses. The Quadruple Bypass burger packs in a whopping 9,982 calories.

Whether you’re waiting at a bus stop or propped up at a bar, chances are a friendly local will strike up conversation – which can feel a little left field if you’re from a more conservative nation. While of course not everybody is interested in talking to strangers, there’s an openness and conviviality that’s uniquely American. It pays to embrace it.

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Most visitors to the US will have eaten peanut butter and/or jelly (jam) in some capacity, yet putting them together is a uniquely American affair. The classic PB&J sees two slices of soft white bread laden with equal parts peanut butter and jelly sandwiched together. The first reference to this creation was by a woman named Julia David Chandler in a culinary magazine dating back to 1901.

Food and soda servings aren’t the only things that are larger in the States – pretty much everything is built on a bigger scale. The highways are wide, the buildings massive, the shop signs luminous and looming. It’s easy to feel pint-sized in comparison.

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While free soda refills are not unheard of in other parts of the world, they’re commonplace across America. Many laid-back restaurants and diners will allow you to top up your cup with as much pop as you’d like, and some places also allow you to guzzle infinite mugs of tea or coffee. The unpractised visitor should exercise caution.

Nearly all US states are divided into counties or their equivalents, but these boundaries hold little significance for travellers and can be confusing when trying to grasp the geography of the vast country. Remember, these are primarily political or administrative divisions, so there's no need to get bogged down by the details when exploring or understanding the US.

The sheer babble and bravado can be overwhelming to any overseas traveller who braves a US sports game. Whether it's baseball, basketball, football or hockey, there'll be brash billboards, blaring music and players with no shortage of celebrity swagger. There’s also the prospect of crowd participation, so giant foam fingers are essential to hide behind if that fills you with dread.

The sporting fanfare isn’t limited to the pros though. The level of adoration and interest awarded to US college athletes is puzzling to visitors – school sports games elsewhere usually pass with little attention from outsiders. Many American students spend hours and hours practising each week, stadiums are filled with loyal supporters, and the games are even televised. 

While nearly everywhere else on Earth has adopted the metric system, most Americans stick to feet and inches. Today, the US takes a hybrid approach (dipping a toe in both systems), and visitors spending any length of time here will need to understand imperial measurements. Time, money and resistance from some of the country’s major businesses has stopped the US from following in the rest of the world’s footsteps.

The legal drinking age in the United States is 21 years old – one of the highest in the world. American bars are also notoriously strict when it comes to checking punters’ ID, regardless of how old you look. Are your twenties but a distant memory? It's still best to come prepared, so nobody misses out on that sundowner.

The nation’s love affair with artificial air never fails to perplex visitors. Cool air is blasted in shops, theatres, cars and restaurants as a constant battle against even the smallest bead of sweat. The root of the obsession is unclear, but visitors should keep abreast of the teeth-chattering temperatures with an extra layer or two.

Hanging from shop fronts, draped over monuments, fixed in front yards – you’ll see the American flag flying proud wherever you go. Most national flags are reserved for official buildings and grand events elsewhere in the world, so America’s patriotic love affair with the stars and stripes takes some getting used to.

There are more than 200,000 fast-food restaurants in the United States – that’s a lot, even for such a large country. The sheer ubiquity of junk-food outlets is staggering too. Though most travellers will be familiar with Colonel Sanders or those golden arches, they’ll be amazed by the fast-food options that can be packed into a single block.

When Americans make a note of the date, they write the month first, followed by the day, finishing with the year. This can be a confusing detail for the foreign traveller – but it’s one you’ll need to get to grips with quickly, or you’ll risk missing that dinner reservation or broadway show.

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If you’re planning some retail therapy during your trip to the US, you had better practice your mental maths. Tax (which varies from state to state, and can be checked online) is excluded from an item’s price tag and added on when you pay. Try and tot it up before you reach the checkout to avoid any nasty surprises.

America’s all-singing, all-dancing malls put many of the world’s dreary shopping centres to shame – and some can be frankly overwhelming at first visit. Though they’re fewer and further between than they once were, a cavernous shopping mall is still the epitome of the American retail experience, and much more besides. The Mall of America in Bloomington, Minnesota is the flashiest of all, complete with its own theme park, aquarium and, of course, hundreds of shops and restaurants.

Though you're not likely to attend, it’s worth being au fait with one of America’s strangest events: the presidential turkey pardon. In a ceremony with all the appropriate pomp, the serving president 'pardons' a turkey to rapturous applause. Thanksgiving follows a few days later. George Bush Senior made the pardoning an official event in 1989 – before this presidents were simply presented with an (unpardoned) turkey. The practice has been baffling foreigners ever since.

America's fondness for ice can puzzle visitors who prefer their drinks at room temperature. In the past, iced beverages were a luxury enjoyed only by the elite – but by the 19th century, America had developed a thriving ice industry, harvesting and exporting ice to warmer regions in need. Today, America's love for ice remains strong, evident in the ubiquitous presence of ice machines in hotel corridors and the standard practice of serving drinks with ice in bars.

If you’re in the USA towards the end of October, the showy Halloween festivities will not go unnoticed. Pumpkins sit plump on every porch, shop windows are bedecked with cobwebs and, on the big night, parades of costumed children take to the streets in pursuit of candy. Travellers not used to such extravagant displays look on in bemusement.

An alien concept to most visitors, 'tailgating' is a party held at the trunk (the boot, to the Brits), or 'tailgate', of the car. They’re commonplace in the parking lots of stadiums and arenas, and usually involve beer, barbecues and some booming speakers. If you see a group of Americans huddled in a car park, smoke rising above the roofs, beats on the breeze, this may well be why.

America’s festivals range from the unusual to the downright bizarre. To name but a few, there’s the Roadkill Cook-off in Marlington, West Virginia; the Humongous Fungus Fest in Crystal Falls, Michigan; the Underwater Music Festival in the Florida Keys; and the annual Mooning Amtrak event, held in Laguna Niguel, Californian on the second Saturday of July. As the name suggests, members of the public arrive en masse to expose their bottoms to passing trains.

Enter any shop in the USA and a buoyant shop assistant will immediately be at your arm begging to help. They’ll pop up at regular intervals as you browse, just to check no issues have arisen since you last updated them. Once you arrive at the checkout, a beaming cashier will probe you about your day. You’ll then be sent on your way, clutching a series of items you only bought to avoid disappointing the spirited staff.

Americans have a penchant for building bizarre structures and leaving them by the roadside. Colourful examples include the life-size dinosaurs in Cabazon, California; the world's largest penny in Woodruff, Wisconsin; a miniature Statue of Liberty replica in Harlan, Kansas; and Cadillac Ranch, a series of psychedelic upturned cars in Amarillo, Texas.

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For those used to disinterested waiting staff and bored bartenders, the relative enthusiasm of American restaurant workers will also come as a shock. After offering gushing recommendations of their favourite dishes, they’ll stop by to check your progress and wait with bated breath as you assure them, through a mouthful of food, that your meal is cooked to perfection. Remember to leave that tip.

If you over-order at a restaurant in most parts of the world, you’ll look on regretfully as the staff whisks away your half-finished meal. This is madness to most Americans, who wouldn’t think twice about requesting the leftovers in a take-home container. The name 'doggy bag' harks back to the 1940s when, during the Second World War, citizens were encouraged to feed scraps from restaurants to their pets at home.

Visitors can easily grasp the enthusiasm for the Super Bowl – in the US, American football rivals the passion Brits have for 'soccer'. However, what baffles many non-Americans is the emphasis placed on the television commercials aired during the event, which sometimes garner nearly as much excitement as the game itself. These ads are extravagant and expensive productions featuring celebrity appearances, presented by global giants like Budweiser, Coca-Cola and Amazon.

In many parts of the nation, public transport is practically non-existent, and the sheer size of the US means most Americans rely on their cars to travel long distances. The great American road trip is both a common movie trope and a fact of life, and the length of time most Americans are comfortable spending in their cars may surprise the foreign visitor.

American cars are giants of the road. The nation’s infatuation with huge SUVs is well-documented – and we can only imagine it’s to match those giant highways.

Unlike the motley dimensions of most world currency, all American bills are the same size. This means you might find yourself fumbling at the checkout, trying to offer a dollar note for something that costs 20 bucks. The assorted names for coins (which bear little or no relation to the actual monetary value) are confusing too: nickels (five cents), dimes (10 cents) and quarters (25 cents). Visitors should get acquainted with them before hitting the road.

While most parts of the world can take or leave summer camp, in the USA, it's a rite of passage. Many Americans you meet will look back fondly on their time frolicking in the nation’s backyard as a kid – and as a trend towards adult summer camp takes hold, big kids are able to get in on the fun too.

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