The number of drivers for the Fourth of July is expected to rise by more than 4% this year, and some cities will be three times more congested than on normal days, according to AAA and analytics company INRIX.
New York City, Boston, Houston and Seattle are all projected to see delays at least three times longer than normal at the busiest travel times. The day and time with the largest delay multiplier varies by city, but Wednesday, July 3, is expected to be the worst day for travel delays overall.
More than 80% of travelers will be driving, according to AAA, with 41.4 million people expected to hit the roads. AAA projects delays to increase by 9% nationally.
"Although travel times are expected to nominally increase throughout the week, hands down, Wednesday afternoon will be the worst time to be on the road," Trevor Reed, transportation analyst at INRIX, said in a statement.
The explosion at the Pennsylvania Energy Solutions refinery could cause prices to rise through the summer, said AAA gas price expert Jeanette Casselano, but gas prices are still down year over year.
"Motorists in the Northeast and surrounding regions are likely to see gas prices moderately increase this summer due to the PES refinery closure," Casselano said in a statement to CNBC on Thursday. "However, the recent bump in the national average, 3 cents since Monday, is mostly attributed to high demand and the upcoming holiday weekend."
Boston and Chicago — which is projected to see two times longer delays — are also both top-10 destinations for July 4th, according to AAA advanced bookings. Orlando, Florida is the top destination.
Click on the map below to see an interactive version showing details of delays in major metro areas.