Throughout most of the world, you must be pretty prominent to have your face featured on your country's currency — but you don't necessarily need to be dead. For example, Britain's Queen Elizabeth II has appeared on coinage in more than 35 countries (that's a Guinness World Record!), including Australia, Canada, Jamaica, New Zealand, and South Africa.

>> Read more trending news

However, the same rule does not hold true for the United States. Only dead people are featured on the country’s coins.

Why? It’s the law.

RELATED: Check your pockets, your coins could rake in millions

In 1866, Congress issued an act stating that no living person can be portrayed on American currency. Our Founding Fathers believed it was unpatriotic for living people's likenesses to be placed on money in circulation. Per The Spruce, George Washington declined to have his portrait on the first U.S. silver dollar. (However, he is now featured on both the dollar bill and the quarter.)

Consider the U.S. Federal Reserve's seven banknotes and six coins. The banknotes have the faces of prominent (and long dead) Americans, including five presidents:

  • $1: President George Washington
  • $2: President Thomas Jefferson (these still exist, but are in limited circulation)
  • $5: President Abraham Lincoln
  • $10: Secretary of the Treasury Alexander Hamilton
  • $20: President Andrew Jackson
  • $50: President Ulysses S. Grant
  • $100: U.S. Ambassador Benjamin Franklin

It's worth noting that Andrew Jackson's likeness on the $20 bill may be replaced by abolitionist Harriet Tubman's. She died in 1913.

The same goes for the coins:

  • Penny: President Abraham Lincoln
  • Nickel: President Thomas Jefferson
  • Dime: President Franklin D. Roosevelt
  • Quarter: President George Washington
  • Half dollar: President John F. Kennedy (these are in limited circulation)
  • Dollar: Sacagawea and her infant son, Jean Baptiste Charbonneau

However, that 1866 law has been broken more than once. A handful of living Americans have been featured on commemorative coins, like Calvin Coolidge, who was president during the country's sesquicentennial celebration in 1926. To recognize the achievement, the Philadelphia Mint released a half dollar with Coolidge and George Washington on the front, and the city's famed Liberty Bell on the back.

The face of Eunice Kennedy Shriver, sister of President John F. Kennedy, was on a silver dollar issued in honor of the 1995 Special Olympics World Games. Shriver, who died in 2009, founded the Special Olympics.

And Nancy Reagan, widow of President Ronald Reagan, was set to appear on the 2016 First Spouse Gold Coin. The coin was released in July 2016, just a few months after Nancy Reagan's death, but was approved and minted before she passed away.

It's important to remember that real people haven't always appeared on U.S. currency. If you are in possession of an old coin without any of the aforementioned Americans on it, it may be incredibly valuable — worth as much as $1.9 million, in fact.

(H/T: CoinTalk)