Slot machines are the most popular form of casino gambling worldwide, and have only become more common with the advent of the internet and the expansion of the iGaming industry. Slot machine history charts the machines’ progress from mechanical novelty to electronic mass-market: the evolution of slot machines is a fast-paced one, closely linked to the rapid technological advances of the past 200 years.
‘Slot machine’ is short for ‘nickel-in-the-slot machine’: during the 19th century, the term applied to any coin-operated machine, including vending machines. Slots history is believed to have started with novelty machines, not necessarily designed for gambling, placed in bars across the US. These rudimentary mechanisms would spring to life with the insertion of a coin, for instance showing two horses racing, and patrons would bet on the outcome.
In 1891, the earliest direct precursor of the slot machine we know today was invented: with five spinning drums containing 50 cards, players would pull a lever and hope for a good poker hand. The establishment would then ‘pay out’ different prizes, such as a free drink, depending on the hand – there was no regulated prizes, and each bar chose their own rules. By using 50 cards instead of the full 52 of a deck, the odds were skewed in favour of the house, providing a house edge even in the earliest forms of the game. However, this system was still relatively complicated, as it required a knowledge of poker (a more obscure game at the time) and also didn’t allow for automated winnings.
In 1895, slot machine history was made by Charles Fey, a car mechanic from San Francisco. His machine, called the Liberty Bell, relied on a simpler system using three drums and five symbols: horseshoe, spade, heart, diamond, and bell. By simplifying the game, Fey was able to create the first slot machine that distributed automated payouts. The Liberty Bell was so popular that Fey quickly couldn’t keep up with demand, and other slot manufacturers starting copying the mechanism, until it eventually started becoming the norm. Other manufacturers added different features, such as Herbert Mills’ Operator Bell, which incorporated the now iconic fruit symbols into his version.
In the early 20th century, gambling was outlawed in the US but was legalised in 1937 in Nevada: following this, the early casinos of Las Vegas were formed. Throughout the following decades, slot machines continued to grow in popularity throughout the US and internationally. They became common in bars, barbershops, cigar shops, bowling alleys and saloons, which were the earliest forms of casino.
The next step in the evolution of slot machines came in 1963 with Bally’s landmark game Money Honey, the first to use electromechanical technology that, unlike the first slot machines, allowed for the machine to track multiple coin and line plays, as well as pay out bigger jackpots.
Slot machine history continued to advance with technology as electronics and microprocessors were developed, with ‘solid-state’ machines with microprocessor technology and display screens becoming popular in the late 70’s. The first video slot machine, dating from 1976, had a 19-inch Sony display screen mounted onto a slot machine frame. This was the model that gained popularity in Las Vegas casinos when these first started booming into the giant gambling industry we know today, which is why modern slots history is closely linked with the history of Vegas casinos.
Other developments, such as the invention of Random Number Generator technology, made the mechanical aspects of the slot machine redundant: machines could simply display a random sequence instead of relying on physical drums, levers, and gear mechanisms to spin and stop the reels of symbols. Following this slot machines ceased to be mechanical and the lever, which had given them the ‘one-armed bandit’ name, became a decorative and nostalgic reminder of slot machine history.
Electronic slot machines allowed manufacturers to incorporate a huge range of themes and visual elements to make their products stand out, and make the experience more immersive and fun for the player. Depending on the theme, different symbols, sounds, and effects were used, with the cabinets being designed to attract players with colourful or distinctive graphics. An important step in slots history at this point was the inclusion of a ‘bonus round’ function, first introduced in 1996 with the game Reel’Em In: adding variety and excitement to the game, this was quickly adopted throughout the industry and has since become a slots staple.
However, the next big step in the evolution of slot machines was to be the popularisation of the internet and of gaming technology. The first online casino was launched in 1994, in the relatively early days of the world wide web, and included online interactive slots using Microgaming technology. Microgaming are, of course, still one of the market leaders in the video slots industry.
Online video slots changed the industry entirely: no longer relying on a physical machine, the game could keep track of complex payout systems and have more lines, with more possible winning combinations. It became cheaper to develop unique, individual games, as there was no need for the physical costs of manufacture and distribution: many developers joined the fray, incorporating games with fully original storylines, graphics, and sound. On the player’s end, they could now play slots from the comfort of their own homes, with huge pooled progressive jackpots.
In the last few years, we have seen the evolution of slot machines go even further, as mobile technology has allowed everyone to have access to unlimited slots anywhere, anytime, through their phone or tablet. In only a handful of generations, slots history has traced the progress from the first slot machines and their simple lever mechanism to a limitless array of unique games which can be accessed at the click of a button for on-the-go gambling.