PHOENIX -- For the first time this decade, AAA is predicting fewer Americans will travel over the upcoming Fourth of July weekend. The auto club's annual Independence Day travel survey revealed that an estimated 40.4 million Americans will travel 50 or more miles from home over the upcoming holiday weekend, a decrease of just over one percent, or 550,000 fewer travelers, from last year.

The western U.S. is slated to produce the largest number of overall travelers with 10.5 million traveling from home, a decrease of nearly 1 percent from last year. Of these, 8.5 million will travel by automobile or RV while 1.7 million, will journey by air. The last time the West experienced a drop in Independence Day travel was in 2001.

According to AAA, all modes of travel have decreased over last year. Eighty-five percent, or approximately 34.2 million Americans, will travel by way of motor vehicle this holiday weekend, while 11 percent, or 4.5 million travelers, plan to travel by air. The remaining four percent, or 1.7 million vacationers, will travel by train, bus or other mode of transportation.

"Four-dollar-per-gallon gas prices are the primary reason why we are forecasting fewer travelers for the second holiday this summer," said AAA Arizona Public Affairs Manager Linda Gorman. "However, it is important to note that a significant amount of the population is still planning to head out of town for the holiday. In fact, we are predicting that 13 percent of the U.S. population and 15 percent of the population from the Western states will travel over the upcoming holiday weekend."

These high gas prices seem to have also indirectly led to a higher incidence of people running out of gas on the highway.

"We can't directly correlate this rise in the number of people running out of gas to the rise in prices at the pump, but anecdotally we know that consumers are trying hard to stretch their dollar and sometimes that means stretching fuel into fumes," said Shelley Beeler, a spokesperson for Allstate Insurance Company.

The number of Arizonans running out of gas on the highway skyrocketed 42 percent in the first five months of 2008 compared to the same time last year, according to the Allstate Motor Club. From January through May of 2008, Arizonans called the motor club for fuel delivery 105 times.

Nevertheless, high gas prices are not the only reason some people are staying home. Higher airfares and rental car rates as well as additional airline fees for luggage are causing some travelers to reconsider their plans.

According to one AAA poll, 23 percent of airline travelers are packing lighter or bringing a larger carry-on bag, and 9 percent are changing their trip plans due to the costs.

The price of a hotel room, on the other hand, has remained constant.