The History of Slot Machines — From the Liberty Bell to Online Slots

The slot machine is the most played casino game in the world. From a single mechanical device built in a San Francisco workshop in the 1890s to a global industry generating hundreds of billions in annual wagers, the history of the slot machine is one of continuous reinvention — each era producing a version of the game that its predecessor could barely have imagined.

Charles Fey and the Liberty Bell (1895)

The first recognisable slot machine was built by Charles Fey, a Bavarian immigrant working as a mechanic in San Francisco. Around 1895, Fey constructed a device he called the Liberty Bell — a three-reel machine with five symbols: horseshoes, diamonds, spades, hearts, and a cracked Liberty Bell. Three Liberty Bells aligned on the single payline paid the top prize of fifty cents.

The Liberty Bell was not the first coin-operated gaming device, but it was the first to use an automatic payout mechanism. Earlier machines — including poker-themed devices built by Sittman and Pitt in New York around 1891 — required an attendant to pay any winnings. Fey’s innovation was mechanical self-payment, which made the machine operable without supervision and created the model for every slot machine that followed.

Fey could not patent his invention fast enough to prevent imitators, and the Liberty Bell design spread rapidly across bars, bowling alleys, and shops throughout California and beyond.

Fruit Machines and the BAR Symbol

In the early 20th century, anti-gambling laws in many American states made cash-paying slot machines illegal. Manufacturers adapted by replacing cash prizes with non-monetary rewards: chewing gum, sweets, and tokens. The symbols changed to match: cherries, lemons, watermelons, and plums replaced the Liberty Bell’s playing card suits. A stylised pack of Bell-Fruit Gum gave the world the BAR symbol, which still appears on classic slot machines today.

The Industry Novelty Company and Mills Novelty Company were major early producers, distributing fruit-symbol machines widely across the United States. The association between slots and fruit was so durable that British slot machines are still called fruit machines to this day, and fruit symbols remain a staple of classic-style slots everywhere.

Electromechanical Slots (1960s)

The next major transformation came from Bally Technologies, which in 1963 released Money Honey — the first electromechanical slot machine. Money Honey used electrical components for its payout mechanism while retaining mechanical reels, allowing it to offer a bottomless hopper and automatic payouts of up to 500 coins without an attendant. It was also the first slot to feature flashing lights and amplified sound, setting the template for the sensory experience of modern slot play.

Electromechanical technology allowed more sophisticated game mechanics. Multiple paylines became practical, payouts could be more varied, and the machines were more reliable than their purely mechanical predecessors. The electromechanical era ran from the 1960s into the 1980s and dominated both American and European casino floors.

Video Slots (1970s–1990s)

The video slot — a machine that displays the reels on a screen rather than spinning physical drums — was developed in the mid-1970s. Fortune Coin Co. created the first video slot in 1976, using a modified Sony television as the display. The machine was initially installed at the Hilton Hotel in Las Vegas. Sceptical players needed time to trust a screen-based game, but the format gradually gained acceptance.

International Game Technology (IGT) acquired Fortune Coin and became the dominant force in video slot development through the 1980s and 1990s. Their Fortune I and subsequent machines established video poker and later video slots as mainstream casino products. The 1994 Reel ‘Em In from WMS Industries is often cited as the first video slot with a true second-screen bonus game — a feature that became standard across the industry.

By the late 1990s, video slots had replaced electromechanical machines on most casino floors and offered five reels, multiple paylines, themed graphics, and bonus features that mechanical predecessors could never have accommodated.

Online Slots (1994–present)

The first online casinos launched in 1994 following the passage of gambling legislation in Antigua and Barbuda. Early online slots were simple three-reel games with basic graphics, closely modelled on their physical equivalents. The limitations were practical: slow internet connections and early browser technology could not support complex games.

Microgaming, one of the first online casino software developers, launched what is widely considered the first online casino software in 1994 and introduced Mega Moolah in 2006 — a progressive jackpot network slot that became one of the most famous online games in history. NetEnt, founded in 1996, established the Scandinavian design tradition that would dominate online slot aesthetics for decades, releasing landmark games including Starburst (2012) and Gonzo’s Quest (2011).

The smartphone era, beginning around 2010, shifted most online slot play to mobile. Developers rebuilt their engines for touch interfaces and smaller screens. HTML5 replaced Flash as the standard technology, enabling games to run natively in mobile browsers without plugins.

The 2010s brought structural innovation: Big Time Gaming’s Megaways engine (licensed from 2016) introduced variable-reel configurations and enormous ways-to-win counts. Developers including Nolimit City and Hacksaw Gaming pushed volatility to extreme levels, building games with maximum wins of 50,000x or higher that attracted a new generation of high-variance players.

Today’s online slot market features thousands of titles from hundreds of developers, regulated across dozens of jurisdictions, played on every device. The Liberty Bell’s three reels, one payline, and five symbols have become a 7-reel, 117,649-ways engine with cascading symbols and real-time multipliers — but the fundamental act of pressing spin and watching the outcome has never changed.

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For how modern slot machines work mechanically and mathematically, see How Slots Work. For a guide to the different formats that emerged from this history, see Types of Slots. Play free slots online and see how modern games deliver on this history.