The first written account of a game with similar rules can be traced back to 17th century Spain, when Miguel de Cervantes wrote a series of novellas called Novelas Ejemplares. One of the stories was about two characters who played a game called ventiuna, which is Spanish for 21. It didn’t have the rules of blackjack, but there were clear similarities. The story was written between 1601 and 1602, implying that people had been playing ventiuna even before then.
Some historians believe that the game we know as blackjack today was first played in French casinos towards the end of the 17th century. It was called Vingt-et-Un (21), and derived from Chemin de Fer and French Ferme, two card games that were popular in France at the time.
There is also a theory that the ancient Romans may have played an early from of blackjack. The Romans enjoyed gambling and played a game where wooden blocks held different numerical values.
While it is unclear who invented blackjack, the game as we know it today really began when the state of Nevada legalised gambling in 1931. It was still known as 21 and it quickly became popular in the first Las Vegas casinos. To attract more players, some casinos introduced a special rule: a hand with either of the black jacks (jack of spades or jack of clubs), with the ace of spades would win at odds of 10-1 – hence the name blackjack. This rule didn’t stick around for long but the new name caught on.