PORTLAND, Ore. -- Travel experts think high gas prices are one of the reasons why fewer Americans plan to travel this Labor Day weekend, according to a recent report.

After a steady rise all summer, gas prices were finally falling in August, down nearly 50 cents per gallon nationally and in Oregon and Washington, experts reported Friday.

However, drivers were still paying about a dollar more per gallon than this time last year, experts said. For that reason, AAA said it expects a one-percent drop, which will be the biggest in eight years, of the number of Americans who plan to travel 50 miles or more. That's about 320,000 people.

More: Find cheap gas prices near you

This will mark the third-straight holiday period with a decrease in travel, Oregon travel experts said.

Tropical Storm Gustav could also change gas prices. It's expected to strengthen into a hurricane as it enters the Gulf of Mexico and could cause a significant shutdown in offshore petroleum production. A number of energy companies began evacuating workers from Gulf rigs earlier this week in anticipation of Gustav, according to the Houston Business Journal.