The reason: Las Vegas McCarran actually grew faster than DIA, boosting its plane boardings by 1.2 million and moving up a notch to the No. 5 position, according to data released Thursday by the Bureau of Transportation Statistics.
Boardings at DIA increased by about 344,000 to end the year at 20 million, ranking it as the nation's sixth-busiest airport. Las Vegas McCarran edged out Denver with 20.5 million passengers boarded in 2005.
"We still had good growth last year, but apparently the Las Vegas area is growing like crazy," DIA spokesman Steve Snyder said. "It's nice that we were fifth, but there's really not much to it other than bragging rights."
The nation's top four airports in 2004 - Atlanta's Hartsfield-Jackson, Chicago O'Hare, Dallas-Fort Worth and Los Angeles International - held their respective rankings in 2005. Orlando slipped a notch to No. 11, replaced by Houston Bush Intercontinental.
DIA's overall passenger traffic, which includes arriving and departing travelers, set a new airport record last year.
But its slide in the nationwide rankings isn't necessarily surprising.
Both Las Vegas and Phoenix are experiencing huge population and housing booms, helping generate a wealth of new air traffic in those cities.
The Boyd Group, an Evergreen-based aviation consulting firm, had previously estimated that Las Vegas and Phoenix will surpass Denver in airport traffic by 2010.
DIA ranked behind both Las Vegas McCarran and Phoenix Sky Harbor in plane boardings during the first six months of 2005. But it finished the year with about 500,000 more enplanements than Phoenix.
"Obviously you've got two cities in the Southwest that are growing dramatically," said Tom Clark, executive vice president of the Metro Denver Economic Development Corp. "Vegas is a hot market right now, but I suspect over time that is not going to be the case. I don't see this as a trend at all, although if next year we drop to eighth, then we might want to look more closely at it."
DIA could climb back into the fifth spot this year.
The arrival of Southwest Airlines in January helped boost DIA's traffic by 8.3 percent during the month compared with a year ago. Denver's two largest carriers - United Airlines and Frontier Airlines - both plan to add flights and routes in coming months, and Southwest is trying to secure another gate.
"All indications right now are that we're going to get some good growth this year, maybe about 8 percent," said DIA co-manager Turner West, who will become manager of the airport next month.
Overall, the nation's carriers flew 4.1 percent more domestic passengers last year than in 2004, even as the number of flights was relatively unchanged, according to BTS data. Load factors, a measure of how full planes were, rose 2.7 percent.
Dallas-based Southwest led all other airlines with about 88.5 million boardings nationwide, and United ranked fourth with 55.2 million. Denver-based Frontier came in 20th with 7 million, up from 6.2 million in 2004.
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