Keno is one of the oldest documented games of chance in human history. According to ancient writings, the game was invented around 200 B.C. by a Chinese warlord named Cheung Leung. His city had been at war for many years; his army was running out of supplies and armament, and the city treasury was virtually empty. Residents of the city, weary of the long years of violent conflict, refused to contribute any more to the war effort. Desperate to raise money, Cheung Leung created a game of chance wherein people could select characters from the Chinese alphabet and win money if their character was pulled in a random drawing. This new game was so popular that Cheung Leung was able to raise more than enough money to supply his army, and the city was saved from financial and military ruin.

In the mid 1800s, Chinese immigrants who flocked to the United States to help build railroads in the West brought their age-old game with them, and it became known as “Chinese lottery.” For years, though it was illegal under U.S. antigambling laws, the Chinese-American community kept the game alive. At some point, probably to make the game more enticing to non-Chinese, the field of Chinese characters was replaced with a field of numbers, and people chose which numbers they thought would be pulled in the drawing.

When Nevada legalized gambling in 1931, the law still barred lotteries. But the new gambling halls recognized the potentially huge profitability of Chinese lottery, so to get around the prohibition, they changed the name of the game to “horserace keno.” Under this new name, the numbers ostensibly represented horses, and gamblers bet on which horse would win the “race” — that is, which number or numbers would be pulled. Eventually, when lotteries were legalized, the game's name was shortened to “keno.” But the “horserace” association persists even today. Most casinos refer to individual drawings as “races,” and if you play more than one game with the same numbers, you are said to be playing a “multirace” ticket.