The first buffet in Las Vegas was at El Rancho Vegas, also the first casino on what is now known as the Strip, which opened in 1941. In an effort to keep gamblers on-property as long as possible, in 1946 owner Beldon Katleman started the concept of the 24-hour "chuck wagon," known as the Buckaroo Buffet. Originally priced at just $1, it featured a simple array of cold cuts, plus a few hot dishes, for an ultra-low price. Our understanding was that it started as just a graveyard option, although a flyer in UNLV's Special Collections indicates that it was 24 hours (there's no date on the flyer, so this may have been a later development).
When the fixed-price all-you-can-eat idea proved to be a roaring success, it was quickly immitated by other operators all over town, keen to keep hungry patrons gambling 24/7 without having to cover the expense of a full-service restaurant. From its late-night origins, the next development was a conversion to daytime hours, as Anthony Curtis described in an article for the L.A. Times that he's pretty sure was the last piece he ever agreed to write as a freelancer-for-hire: "The Last Frontier and the Dunes are given credit for serving the first 'hunt breakfasts,' which were the forerunners of the Sunday champagne brunch. And gradually, through the sixties and seventies, the breakfast, lunch, and dinner format replaced the graveyard hours.
"Well into the seventies, inflation was still an unknown on the buffet scene. The most opulent spreads at Caesars Palace and the Dunes were $2.75 and $4, respectively. The vaunted Silver Slipper dinner buffet could be had for just $1.98. The ultra-low prices finally began to be phased out in the eighties following the success of higher priced, higher quality, offerings at the Sands and the Golden Nugget. What I call the 'new' Las Vegas began to take shape in the late eighties, and it was then that the buffet standard rocketed upward to keep pace with the rest of the town."
Today, Las Vegas remains the buffet capital of the world, with the concept continuing to evolve in the shape of multiple-property passes, for example, in response to the continued need for cheap, diverse, and convenient eats.