Planning to travel for the Fourth of July? You’re not alone.

Experts say the holiday weekend will be one of the busiest for car and air travel since the start of the pandemic.

More than 660,000 people living in Philadelphia and its collar counties are expected to travel 50 miles or more by Monday, despite gas prices reaching their highest level since 2014, AAA Mid-Atlantic told CBS Philly. The national average is over $3 a gallon.

» READ MORE: Your ultimate 2021 July 4th guide to Philly

“The great American road trip has returned,” Jana Tidwell of AAA said.

Travel got off to a rough start Friday morning, when I-95 south of the Pennsylvania-Delaware border was closed due to a truck fire, leading to lengthy traffic backups and congesting local roads. No injuries were reported.

The Pennsylvania Department of Transportation urged motorists to check before hitting the road to review any interstate highway restrictions that might be in place this weekend.

At Philadelphia International Airport, officials expect to see 340,000 passengers by Monday. That’s on top of the 2.4 million passengers who passed through the airport in June — the most since the pandemic began.

On Friday morning, the airport announced that its parking garages are full, and officials encouraged air travelers to get a ride from a friend or use public transportation.

Fourth of July festivities happening in Philadelphia are expected to draw crowds, too.

SEPTA announced plans to expand service on Sunday for the fireworks on the Parkway, including six Broad Street Line express trains leaving Fern Rock every 10 minutes from 6:10 p.m. to 7 p.m.

In addition, select Regional Rail trains will be added to the service schedule, or held later than regularly scheduled, for customers leaving Center City after the fireworks, and the Mann loop will provide bus service for the Wawa Welcome America Concert.

SEPTA bus routes that operate in the area of the Parkway will be detoured because of the fireworks.