Holiday travel is starting, and with more than 55 million people projected to travel during the upcoming holiday week, it will be busy out there. In fact, more than 3.2 million people are expected to fly in the U.S. on the Sunday after Thanksgiving alone.

At many airports across the country, with all those passengers in the air, many cars fill the parking lots. In the last few years, we've seen airport parking lots hit capacity several times, and we expect that to happen in some spots again this week. Some airport social media accounts are already offering some warnings to that effect.

To ensure there's a spot for your car where you like to park at the airport, the safest bet is to go ahead and lock that reservation in now. Sometimes, those who book in advance can also save some over the drive-up rate.

On the airport's website, you can likely go to the parking reservations page, input the day or time you'll arrive at the airport and indicate when you plan to leave. You can also select which terminal you'll be using.

Booking in advance can save you money, too

Another thing to remember is that by booking your parking and paying in advance, you can often tap into some savings. These savings can go as high as 50%, though savings during holiday times may not always be quite that high.

Bottom line

When hustling to make a flight during the busy holiday travel season, the last thing you want to do is have to drive in circles for 20 minutes searching for an airport parking space — or not be able to get into the parking lot at all.

Since airports offer parking reservations, if you know now that you'll be flying — and driving to the airport — it's likely best to go ahead and lock in your space now.