With travellers increasingly conscious of their carbon emissions, a new guide outlines the US routes where it would make the most sense to swap a plane trip for a train journey.

According to Hipmunk, the most comfortable, convenient and cost-effective alternative to a plane ride is taking the train, and by doing so, you cut carbon dioxide (CO2) in half compared to a plane ride covering the same distance.
Read more: Getting around the US by train
To help users make an informed decision as to whether it would be worthwhile swapping the plane for a train, it has published data showing Amtrak train trips alongside flight results on routes where Amtrak provides service. It provides the train schedules and prices where available and shows users whether the train has Wi-Fi.

"We did a deep dive on our train data (as it compared to flights), examining everything from savings to the most popular routes to in-trip travel time," says Hipmunk. "So whether you’re looking to avoid crazy airports during peak season or searching for a more eco-conscious way to travel for business, here’s all the information you need so that you can make the smartest decision for your trip."

The most popular train routes are short routes connecting highly-trafficked business and tourism cities in the northeast, such as New York City to Washington, DC, where passenger rail captured a much as 75% of the market in 2012. For travellers looking to save money, cost certainly appears to have factored into travelers’ decisions to choose Amtrak over a plane, as trains were the definitively cheaper mode of transportation.
Read more: 10 of the world's most amazing train journeys
In fact, for the 100 most-booked Amtrak routes on Hipmunk in the past year, a train trip was the cheapest option 80% of the time. To have a look at the top 25 most popular routes, plus the in-trip time difference, please see here.