AAA reports a national average price of $2.74 per gallon, up about 1.5 percent from the start of the week and close to 2 percent more than one week ago. The motor club attributed much of the increase to a rally in crude oil prices, Oil prices, which represent more than half the price at the pump, are up more than 30 percent since the start of the year.

Some U.S. states on the West Coast have passed the $3 per gallon threshold in recent days, though the rate of increase has largely mirrored the national average. South Carolina had the lowest state average in the nation at $2.43 per gallon.

More than half of all U.S. states reported an average price below the $2 per gallon mark in late 2014. Both AAA and analysts at the price watchdog group GasBuddy said higher gasoline prices won't keep travelers off the road during the long Memorial Day weekend.

More than 33 million travelers are expected to hit the roads for Memorial Day, the highest in 10 years and up 5.3 percent from last year, AAA said. In a survey of more than 150,000 members, GasBuddy said Memorial Day is the top holiday weekend for road travel.

AAA, however, finds drivers are experiencing "significant" savings at the pump when compared with last year. Today's average price is nearly $1 less than this date in 2014.

"Even with the current uptick in gas prices, we predict most U.S. travelers will pay the cheapest Memorial Day gas prices since at least 2009," Patrick DeHaan, senior petroleum analyst for GasBuddy, said.

In a short-term market report for May, the U.S. Energy Information Administration said it expected the national average price for full-year 2015 to level out at around $2.43 per gallon. The full-year 2014 average was $3.36 per gallon.