Record-high gas prices won't stop nearly 3.1 million Southern Californians from leaving home this Memorial Day weekend, according to the Automobile Club of Southern California.

But with a gallon of gas selling for anywhere from $3.35 to $3.75 locally, many holiday travelers won't venture too far. Instead, they'll likely take shorter trips, according to the American Automobile Association, which is affiliated with the Automobile Club of Southern California.

Many weekend trips are likely to be 70 miles or less.

John Francisco decided to get an early start on the Memorial Day weekend, driving Tuesday from the Brentwood section of Los Angeles to Camarillo for a short getaway.

"If gas weren't so expensive, I might have driven farther," said Francisco, as he stood next to his Toyota 4Runner at the Camarillo Premium Outlet stores. But with his SUV averaging less than 20 miles per gallon, Francisco said he likely won't travel farther than Ventura County.

Nationwide, the average retail price of unleaded gasoline was $3.10 per gallon last week, according to AAA and the Oil Price Information Service.

More than 80 percent of Southern California travelers some 2.6 million people will travel by car this weekend, 1.7 percent more than last year, according to the Automobile Club of Southern California. Another 455,000 are expected to fly, 1.4 percent more than 2006.

San Diego tops the list of the most popular destination for Southern Californians this weekend, according to an AAA Travel survey. Las Vegas comes in second, followed by the Grand Canyon. The Central Coast places fourth, followed by the San Francisco Bay Area.

The Memorial Day weekend comes on the heels of a study showing prices at the pump increased 32 percent in inflation-adjusted terms from December 2006 through the middle of May.

Adjusted for inflation, gas prices are the highest since June 1981, according to the study released by the Center for American Progress, a policy research and advocacy organization based in Washington, D.C.

"If prices go up just a little bit more, they'll be at their highest since the 1920s," Christian Weller, one of the study's authors and a senior fellow at the center, said during a Wednesday news conference.

Weller said the high prices are having an impact on the spending habits of many American families. With the average passenger car getting just 22.9 miles per gallon, with gas at around $3.50 a gallon, it costs $91.70 in gas to travel 600 miles.

The high price of fuel also is making air travel more expensive, Weller said.

The California Highway Patrol and numerous other law enforcement agencies across Ventura County plan to crack down on motorists who drink and drive this weekend. The CHP and 13 other agencies, including Santa Paula and Oxnard police, will establish a sobriety checkpoint in Santa Paula from 7 p.m. Saturday to 1 a.m. Sunday.

Ventura County Sheriff's deputies also will work overtime this weekend to accommodate DUI arrests, according to an Oxnard police news release.

Officers arrested 287 DUI suspects countywide during an 18-day campaign at the end of 2006.

"We'll be doing everything possible to keep drunk drivers off the streets this holiday weekend," said Humberto Jimenez, a senior officer with the Oxnard Police Department.