WASHINGTON, D.C. -- In the early 1960s, no states ran lotteries, only one - Nevada - allowed casinos, and Indian tribes had yet to discover bingo or glitzy casino halls.
Today, 42 states operate lotteries, 37 have commercial, Indian or racetrack casinos and only two - Utah and Hawaii - don't allow any form of gambling.
The gaming industry is a billion-dollar business in the United States, raking in $84.8 billion in 2005 alone. And revenues are rising steadily.
"Gambling has become part of American life," said I. Nelson Rose, a gambling law expert at Whittier Law School.
Much of the industry's growth is being fueled by Indian gaming, which boosted its revenues by nearly 20 percent in 2005 from the previous year, according to a study released recently by Casino City Press.
The overall gambling industry grew at a slower pace of 6 percent, according to the industry group's North American Gaming Almanac. While lotteries and commercial casinos saw modest growth in 2005, race and sports betting continues to decline - a slump some experts attribute to the growth in Indian gaming.
A relatively young business, Indian gaming has seen its revenues skyrocket in recent years, as more and more tribes open bigger and better casinos.
These casinos now include some of the largest gambling properties in the country, such as Connecticut's Mohegan Sun, a 300,000-square-foot casino owned by the Mohegan Tribe.
Also in Connecticut, the Mashantucket Pequot Tribal Nation boasts the largest casino in the world, Foxwoods, which features 340,000 square feet of gambling space, dozens of restaurants and nearly 1,500 hotel rooms.
"The industry is only 10 or 15 years old," said Nancy Conrad, a spokeswoman for the Agua Caliente Band of Cahuilla Indians, which operates two casinos in Southern California. "In many cases, it's ... developing and growing."
Currently, 226 Indian tribes operate about 400 gambling operations in 28 states - about twice the number of facilities open just a decade ago, according to the National Indian Gaming Commission.
Gambling is not a new phenomenon in the United States. The first American colonies were funded by lotteries in England, and the country's early settlers often sanctioned lotteries to raise money for public works projects.
Public lotteries have gone in and out of favor since the early 1600s, but they began a resurgence in the 1960s after New Hampshire became the first state to launch them again.
Much of the stigma that used to surround gambling has eroded in the past several decades, after churches began operating bingo halls and state governments started running their own lotteries in the 1960s, Rose said.
Industry experts say Americans' acceptance of gambling in recent years is partly fueling the growth in demand. At the same time, Indian casinos such as the Mohegan Sun and Foxwoods have become destinations in their own right, rivaling the best gambling halls on the Las Vegas Strip.
Indian casinos also are often closer to home for more Americans across the country. Only 11 states have commercial casinos, notes Holly Thomsen, a spokeswoman for the American Gaming Association.
"More people are exposed to native casinos than commercial casinos," Thomsen said, "The majority of growth has been in that sector."
But that growth could begin to slow as the Indian gaming industry matures, Rose said. For now, however, he says Indian gaming is the "latest boom industry."
"The tribes often have terrible locations," he said. "But when they have good locations, it's often a monopoly or close to it."