The first slot machines were designed by Pitt and Sittman in New York in 1891. It had five drums that would show poker hands. It didn't have any payout mechanism so the places that use them would pay the prizes on their own, most commonly free drinks.
Then in 1895 Charles Fey made his first slot machine in his basement. The Liberty Bell, so named because of the sound that it made when someone hit a winning combination. It was made of over 100 pounds of cast iron and didn't have the fruit symbols that modern slot machines today have. It had suits from playing cards such as spades and diamonds as well as stars and horseshoes.
By 1907 Charles Fey decided to partner with Mills Novelty Company and produced a new version of the machine which they called Operator Bell. This machine carried the now famous fruit symbols on its reels. Since these machine weighed so much and cumbersome to move around, Mills made a lighter more portable version made of wood in 1915.
The Mills Company branched out and created more slot machines for the growing number of intrigued players. In 1930 they made some ground-breaking changes to the original slot machines. They made the new slots less noisy and added a double jackpot feature. This allowed players to win twice in a string of plays.
They also worked on different designed for the machines which gave rise to themed slots. It made the game more popular and enticed a whole slew of new players and made the slot machine industry game boom throughout the United States.
As with any other gambling game, the slot machines were bombarded be legal issues and protest. It became illegal in San Francisco in 1909 and was banned in Nevada a year later. In 1911 the state of California made it a state-wide ban. In New York, Mayor La Guardia ordered the dumping the slot machines at sea, even though some of them were only vending machines.
Bugsy Siegel, an infamous underground figure, who built the Flamingo Hilton on the Las Vegas strip invested on slot machines to fill up his casino floor and keep his rich friends' wives and girlfriends entertained.
The slot machine grew in popularity in the United States and eventually, the world. It now accounts for 70-80% of casino revenues. This highly profitable and entertaining machine has made casino owners into corporate moguls. It has developed from Fey's 100-pounder of a machine to what we know as noisy and brightly-lit machines.