Today, Nevada's gaming industry is a juggernaut; the largest in the United States and second largest in the world, with annual casino revenues of more than $11 billion. About 80 percent of that revenue comes from Las Vegas. But it wasn't always that way. The five dates discussed below are significant milestones that show how Las Vegas developed its dominance--and how it is hoping to retain it in the future.

March 19, 1931: Commercial Gambling (Re) legalized

This is the day that changed everything. Contrary to popular belief, A.B. 98, which Governor Fred Balzar signed into law on this day, didn't "legalize gambling" in Nevada. Rather, it brought back "wide open" gambling. Here's the difference: In 1869, Nevada first legalized commercial gambling, which back then was primarily card and dice games played against the house. In 1909, thanks to Progressive opposition, the state criminalized gambling, though over the years a series of carve-outs allowed low-stakes social games -- pastimes like poker, played against other players and not against a central bank.

In early 1931, reeling from the effects of the Great Depression, lawmakers considered returning to a regime of "wide open" gambling, which would allow commercial establishments to bank games once more. When Balzar signed the law, it again became legal for saloons and hotels to offer games like craps and blackjack. The first gambling halls were small, but this was the origin of today's international commercial casino industry.

April 3, 1941: The Strip is Born

Originally, gambling in Las Vegas was small-scale. Mostly confined to downtown clubs and a few small roadhouses on Boulder Highway and Highway 91, the artery leading south to Los Angeles. But that all changed when California hotelier Thomas Hull opened the doors of the El Rancho Vegas, the first self-contained casino resort on what would, over the next decade, become the Las Vegas Strip.

Gambling in Las Vegas had been around since 1931, but for the first time at the El Rancho Vegas, it became part of a larger resort complex that could appeal to both casual vacationers and serious gamblers. With only 63 rooms at opening, it was a fraction of the size of today's Strip megaliths, but it had all the elements -- gambling, dining, lodging, entertainment, retail -- that Strip resorts have today.

August 5, 1966: An Empire Rises

The model for the Strip casino resort had been set for over two decades when the first really new idea came to Las Vegas. Before Jay Sarno opened Caesars Palace, Las Vegas casinos were exciting without being exceptional; visitors gambled, drank, ate, and were entertained, but they were never wowed. That changed with Caesars Palace, whose thorough theming (even the stationery features burned edges, reminiscent of Rome burning while Nero fiddled) put it head and shoulders above the competition.

Jay Sarno, the compulsive gambler and relentless dreamer who conceived and realized Caesars Palace, saw the direction that Las Vegas would take: serving up not just freedom from rules, but fantasy unleashed. Until the next pivotal date, Caesars Palace would continue to be the most successful casino on the Strip--a reign of 23 years. Today, it remains the most recognized casino name in the world, and it's the flagship of Caesars Entertainment, one of the world's largest casino operators.

November 22, 1989: Presenting the Dream

The 1980s started off bad for Las Vegas, but got better. The early-decade recession forced casinos to reevaluate everything, and by the middle of the decade, most had started chasing middle-market gamblers, who made up in numbers what they lacked in bankroll. The result was a series of expansions and renovations that bulked up the Strip but left an opening in the market: no one had added facilities that catered to upscale visitors for years, and the last major resort opening was in 1973. Atlantic City had opened nearly a dozen new casinos since 1978, and had surpassed the Strip in win in 1983.

So it took vision and courage to build something new, large, and geared toward the high end in Las Vegas. Steve Wynn had both: The Mirage was the largest casino resort built from scratch to date, and it had an unprecedented range of nongaming, nonrevenue-producing elements -- a rainforest, a white tiger habitat, and a Strip-front volcano among them.

Many of the Strip's most seasoned operators predicted an ignominious flop, but Wynn and his team knew they had a winner. They were right. The first night, 50,000 guests showed up, and until Wynn opened the Bellagio nine years later, The Mirage was the undisputed champion of Las Vegas Boulevard. The Mirage provided the model not just for other Wynn casinos, but for the subsequent development of the Strip.

April 30, 2013: Stepping into the Next Frontier

Betting on the Internet isn't new; real-money sites have existed since 1995. But the United States has been much slower than other nations to create a framework for legal online gambling. After a December 2011 Justice Department opinion opened the door for states to regulate gambling over the Internet within their own borders, Nevada began developing the rules and procedures that would permit companies to offer online poker to those within the Silver State.

It took time for online providers to develop geolocation, identity verification, and security protocols that met regulators' standards, but in the spring of 2013 Ultimate Poker opened the first legal, state-regulated online poker game in the United States. The Station Casinos subsidiary remained Nevada's only online poker provider until Caesars Entertainment's WSOP.com launched that September.

Today, there are three Nevada-based online poker sites, a compact with Delaware permitting the sharing of player pools across state lines, and the promise of future growth as other states approve online play. As with commercial gambling, the first step was a single milestone on a long journey.

(Archival photos courtesy of UNLV Special Collections)