There’s no question that the threat of COVID-19 has had a significant effect on how Americans travel. Summer, which is typically vacation season, has seen millions cancel or postpone plans to traverse the country.

While travel by any means may increase your odds of coming in contact with the virus, some methods are safer than others. Recently, Condé Nast Traveler spoke with a number of health experts for guidance on how to approach vacations via air, train, or the highway. The general consensus? If you’re going somewhere, try to go by car.

Air travel presents a number of scenarios where risk of transmission increases. Passengers have to wait in long lines where physical distancing will be difficult. Once on a plane, they could be seated fewer than 6 feet from other passengers. While airplane cabins do have highly effective air filtration systems, being close to someone infected still presents the very real possibility of being exposed to germs. A lack of uniform regulations about masks and distancing for airlines also means that procedures for reducing the risk of transmission may or may not be observed.

It’s important to note, however, that a recent study by the Massachusetts Institute of Technology found that the risk of contracting COVID-19 from a passenger during a two-hour domestic flight is just 1 in 4300. If the middle seat is blocked off, thereby increasing the distance between travelers, the risk drops to 1 in 7700. While that doesn’t mitigate the risk of standing in long security screening lines indoors, it does indicate that air travel may not be inherently high-risk.

Travelers can further reduce the risk of infection if they opt to travel by train. In addition to having less congestion in passenger compartments than airplanes, lines usually form outdoors. But train trips also tend to be longer than flights, and the duration of exposure to someone infected can influence the risk of transmission.

So why is traveling by car superior? Unlike communal travel, cars afford a level of control. People can travel with members of their household with a known health history and don’t need to share space for extended periods with strangers. There is still risk in stopping and entering public spaces like restaurants, but physical distancing is more manageable in those scenarios than on a long-duration plane flight or train ride.

“If you have to—and can afford it—I think traveling by car is the safest option right now, in part because you’re not traveling with another person whose risk of infection may be unknown,” Chris Hendel, a medical researcher associated with the USC Gehr Family Center for Health Systems Science and Innovation, told Condé Nast Traveler. “Essentially you aren’t sharing the breathing space with someone who could be infected. But of course, one needs to be very cautious about stopping while traveling by car. I think train travel might possibly have an edge over air travel. Regardless, everyone should be wearing a mask on the train or in the plane.”

If you do decide on a road trip, it’s a good idea to limit exposure to others for 14 days prior to your departure so you reduce your chances of becoming infected before to your trip or transmitting the virus during it. When stopping to use a bathroom—often the riskiest portion of highway travel due to being in a confined space with others—try to find a single-occupancy restroom if possible and make sure you wear a mask. And eat somewhere with outdoor seating if you can. 

[h/t Condé Nast Traveler]