American Roulette
After being invented by the French in the 18th century, the game of Roulette made its way to North America as the 19th century began. It followed the trade route across the Atlantic and up the Gulf of Mexico to New Orleans, where it was readily embraced by the local French enclave.
During the time of the Louisiana Purchase in 1803, all Roulette wheels featured 38 numbered pockets. Their alternating red and black numbers formed semi-circles between a zero on one side of the wheel and a double zero on the other. It was not until 40 years later that a 37-pocket version of the wheel would be created for standard use in European casinos. By then, the original wheel would be entrenched in the saloons and gambling halls of America’s Old West, and so it has remained, unchanged to this day.
Playing with 38 Numbers
The American Roulette wheels seen in today’s casinos feature exactly the same layout as the ones installed on riverboats that navigated the Mississippi River over two hundred years ago. The numbers run clockwise from the single zero in what appears to be a random order: 0-28-9-26-30-11-7-20-32-17-5-22-34-15-3-24-36-13-1-00-27-10-25-29-12-8-19-31-
18-6-21-33-16-4-23-35-14-2.
Closer inspection, however, reveals that each odd number on the wheel is positioned directly opposite from the next even number in sequence. What’s more, the colors alternate red and black, as shown by putting the numbers from one half of the wheel above the other in a grid, as follows:
When it comes to the roulette table, the American and European layouts are virtually identical. The red numbers slalom down the length of the field like ski track from 1 to 36. The black numbers appear to have been grouped around the 5 and 29, while 17 and 20 are somewhat isolated in the middle of the table.
The biggest difference in the American pattern, of course, is the double zero that sits next to the single zero at the top of the three columns of numbers. This creates a unique betting opportunity in American roulette that cannot exist on the 37-number European version. It is possible to bet a single chip on five numbers as a group: 0-00-1-2-3. On the other hands, this is not a good bet, since the payout is 6-to-1, while the true odds of a hit there are 33:5 against, considerably worse than the implied 30:5.
Odds Favor the House
Having a double zero on the wheel also affects the odds. Any number on a 37-slot European Roulette wheel has a 1/37 chance of coming up, or about 2.70%. On the American Roulette wheel, the probability is 1/38, or 2.63%. The discrepancy may look small, but it has some big ramifications, especially as regards the House edge.
With only one zero on the wheel, the House has a 1/37 or 2.70% advantage over the player. With a zero and a double zero working for the House, it increases to 2/38 or 5.26%—nearly double. When offering American Roulette, a casino expects to collect a little more than one dollar out of every $20 wagered versus just 54¢ at the European Roulette table.
It stands to reason that, if a player has a choice between the two types of Roulette, the smart money is on the European version. But casinos get around this by varying the stakes at the tables. American Roulette can typically be played for as little as 10¢, 25¢, or $1 per chip wagered. European Roulette may start at $2, $5, or more. What the House might lose in advantage, it will make back in betting volume over the long term.