After a plunge in gas prices, Americans are expected to hit the highways in larger numbers this Memorial Day, giving the traditional start of the driving season a boost for the first time since 2005, AAA said Tuesday.

An estimated 32.4 million people - roughly 11 percent of the U.S. population - will take some kind of trip over the holiday, most of them on the road. That's an increase of 1.5 percent from last year's dismal travel season, when pump prices rose above $4 a gallon and millions of people stayed put.

On Tuesday, retail gas prices averaged $2.25 a gallon, about $1.47 a gallon cheaper than a year ago, according to auto club AAA, Wright Express and Oil Price Information Service. Prices have increased 17 cents a gallon in the last week, but experts believe we are near a peak for the year.

Travel researcher Ken McGill used a combination of surveys and economic models to make AAA's forecast. Many respondents told McGill that they were lured by hotel discounts and cheaper gas.

It also appears that many Americans have been suffering from an extended case of cabin fever, McGill said. Because of high gas prices and the souring economy, many people have stayed home during the past few years.

"There's a bit of pent-up demand out there," he said.

Still, McGill said he expects the recession will leave the tourism industry with a particularly miserable summer.

From April to September, Americans are expected to take 20 million fewer trips compared with last year and spend $43 billion less on everything from gasoline to plane tickets to hotel rooms, according to a separate forecast McGill completed in February.

An AP-Gfk Poll released Monday also shows that fewer Americans will be traveling this summer. A third of those surveyed said they've already canceled at least one trip this year to save money.

"While we see a slight uptick during Memorial Day, it's not setting us up for an entire summer of increased travel, over and above what we saw last year," McGill said.

Americans have been cutting back on Memorial Day travel every year since 2005, when 44 million people traveled at least 50 miles from home. Between 2005 and 2008, the national average price for a gallon of gasoline on Memorial Day rose nearly 87 percent.

Last year, Memorial Day travel dropped 9.6 percent compared with 2007 as pump prices headed toward record highs.

The AAA forecast for this weekend expects about 83 percent of travelers will get around in a motor vehicle. Another 7 percent will travel by plane. The remaining 10 percent will travel by train, bus or another mode of transportation.

McGill is the executive managing director travel and tourism services, at Boston-based IHS global insight.