It's going to be another busy Memorial Day weekend on the nation's highways.

From Thursday through Monday, 31.2 million Americans will drive 50 miles or more to a beach, campground, or other getaway, according to the car lobbying group AAA. That's a small increase from last year but still well short of the record 37.3 million who drove during the holiday in 2005.

Gas will cost slightly more this year. The national average price for a gallon of gasoline has risen seven cents in the last week to $3.66 and could increase over the weekend. Gas averaged $3.64 last Memorial Day. Still, the price is not expected to reach the 2011 Memorial Day average of $3.79.

The total number of holiday travelers should decline almost 1 percent to 34.8 million, AAA says, because fewer will choose to fly. AAA estimates that 2.3 million travelers will take to the skies, down 8 percent from last year.

"American travelers are experiencing fee fatigue and frustration with everything from higher fares to airport security," Robert L. Darbelnet, chief executive officer of AAA, said in a statement. "As a result, many are choosing road travel."

The airline industry's lobbying group - Airlines for America - said it expected a typical Memorial Day weekend and saw overall summer traffic increasing by 1 percent.

The average domestic round-trip airfare for June, July, and August is $421, down $6, or 1.4 percent, from last summer, according to the Airlines Reporting Corp., which processes almost half of all airline tickets sold in the United States.

The travel forecast done by IHS Global Insight for AAA - one of the nation's largest leisure-travel agencies - is based on interviews with 306 Americans. It also factors in estimates about the overall health of the economy.

In 2012, AAA underestimated the number of people driving on Memorial Day by 400,000. Part of the reason is that its report is prepared more than a month before the holiday. Last year, gas prices fell more than 20 cents a gallon during that period. This year, there was a rebound in consumer confidence after the AAA report was completed, which could indicate a few more Americans will travel than AAA predicts.