The starkest decline among the top air carriers in the market belongs to US Airways, the second-biggest airline at McCarran, which posted a near 24 percent decrease for the month.

United, the third-biggest carrier, posted an 8 percent decline, and the decrease at American, the fifth-largest McCarran airline, was more than 3 percent.

Southwest, McCarran's largest carrier, and Delta, the fourth largest, were the only two among the top five airlines serving Las Vegas to post increases in January.

Southwest carried nearly 1.3 million into and out of the market for the month, an increase of more than 2 percent. Delta moved almost 198,000 passengers, an increase of nearly 7 percent.

The decline at US Airways is part of a major swing in the airline's Las Vegas performance.

In January 2007, the airline moved more than 836,000 customers to and from McCarran, nearly 31 percent better than its performance in 2006.

The figures published Thursday indicate the airline gave back much of the 2007 increase when it moved fewer than 640,000 customers to and from Las Vegas during the first month of this year. The comparisons include numbers posted under the America West name, an airline that merged with US Airways in 2005 but still reported separately in traffic figures in January 2007.

US Airways spokesman Morgan Durrant cited the high cost of fuel for the decline.

Durrant said high prices make it less profitable for the airline to maintain routes to and from Las Vegas, especially when it comes to night flights, which he said fetch lower fares.

"Typically, fares on night flights are less than what they are in the daytime, and we therefore can't offset the cost as well," Durrant said.

It wasn't all bad news for January air service to Las Vegas.

Scheduled service to Terminal 2, the site of most international arrivals and departures, increased 11 percent for the month.

WestJet, a low-fare Canadian carrier, posted an 82 percent increase. Philippine Airlines increased almost 62 percent and Hawaiian Airlines increased more than 2 percent.

Contact reporter Benjamin Spillman at bspillman@reviewjournal.com or (702) 477-3861.