Drive-in traffic from Southern California to Las Vegas decreased nearly 1 percent with an average of fewer than 40,000 cars per day crossing the Nevada border on Interstate 15.

But Las Vegas resorts did manage to squeeze more money from visitors no matter how they arrived. The average daily room rate jumped more than 17 percent over May 2006 to $143.

The figures are from a monthly report released Friday by the Las Vegas Convention and Visitors Authority, publicly funded tourism boosters for Southern Nevada.

Occupancy in the Las Vegas area's 133,000 hotel rooms also increased to 92 percent for the month, up 2 percent from the year before with a similar number of rooms.

"It is the strongest May occupancy we ever had," said Kevin Bagger, the authority's director of Internet marketing and research. "That definitely stands out."

For the year through May visitation is up nearly 1 percent to 16.3 million.

The amount of room tax the authority collected in May was unavailable. But in May of last year, when room rates were 17 percent lower, the authority collected $18.3 million.

An increase in convention visitors was another contributor to the overall uptick for the month of May. There were 2,231 conventions in Las Vegas that attracted 506,000 attendees. The number of events was a 2.9 percent increase but the number of people who attended them was up 19 percent.

The amount of money convention attendees left behind also increased more than 25 percent to about $687 million.

Bagger said the return of two conventions boosted the figures. A kitchen and bath show that attracted about 50,000 people returned to Las Vegas for the first time since 2005. A cable and telecommunications show that attracted 14,000 people returned for the first time since 1987.

"It was a strong convention calendar," Bagger said.

Outside Las Vegas tourism was down in both of Clark County's other markets.

In Mesquite, north of Las Vegas on I-15, visitor volume was down nearly 3 percent for the month to about 129,000. Gambling revenue, the amount of money lost to casinos by customers, increased more than 9 percent to $13.9 million. The average daily room rate increased almost 71 percent to $94 and occupancy dropped slightly to 80 percent.

The picture was grimmer in Laughlin, the value-oriented market along the Colorado River south of Las Vegas. The market has been hit especially hard by the expansion of Southern California Indian gaming in recent years.

In May visitation dropped nearly 5 percent to 260,000. Convention attendance was down almost 28 percent and gambling revenue dropped more than 4 percent to $52.7 million.

About the only financial category that increased in Laughlin was room rates, which rose nearly 13 percent to about $46.