LAS VEGAS — Stephen A. Wynn, the hotel and gambling impresario, still remembers the first time he was asked if he and other developers had lost their minds building so many casino hotels here. It was the mid-1970s, when Las Vegas had about 35,000 rooms.

He was asked that same question in the 1980s, while building the 3,000-room Mirage, and again in the early 1990s. By that time Las Vegas was home to more hotel rooms — 106,000 — than any other city in the country.

And so now, with Las Vegas in the midst of another big building boom, Wynn only shrugs when people suggest that the nation's premier gambling center, with 151,000 rooms and counting, simply cannot absorb any more new hotels.

Ever since the mobster Bugsy Siegel opened the first modern hotel casino here in 1946, the surest means for gaining attention has been to one-up the competition by building an even more monstrously immense pleasure palace.

But even Las Vegas has never witnessed anything quite like what is going on today.

"This is the most outrageous, over-the-top expansion" ever, Wynn said.

Americans — and an increasing number of foreigners — can't seem to get enough of Las Vegas. The current construction craze is driven by a 95 percent weekend occupancy rate — and rates that approach 100 percent at the city's newer properties. Last year, even the weekday rate fell just shy of 90 percent, partly because of the city's success in positioning itself as an attractive convention destination.

Fueling the current boom as well are the enticing riches to be made catering to a new kind of guest: aging boomers entering the empty-nest phase of their free-spending lives.

And contrary to some predictions, the opening of American Indian casinos and other gambling outposts in more than 30 states has not hurt Las Vegas.

Far from it. The smaller, more prosaic gambling halls stretched across the country have actually helped the boom, casino executives say, serving as a kind of a feeder system for Las Vegas as people gain a taste for gambling and then aspire to a touch of the big time. The soaring popularity of poker has also helped drive growth as the game has drawn a younger crowd to the city.

"I suppose one day Las Vegas will reach its limit," said Anthony Curtis, president of LasVegasAdvisor.com, a local travel site. "But that day is nowhere in sight."