Amtrak is expanding its pets-on-trains program beyond the Northeast and Illinois, which was where it began two years ago. Now, the passenger rail outfit is making it permanent on some routes, while continuing the pilot program on other routes across the country.

"We are excited to bring this service to more of our passengers throughout the country who want to travel with these cherished family members," said Amtrak President and CEO Joe Boardman in a statement. "We listened to our passengers and delivered on this program, which will also help increase ridership and revenue."  

The big news for Northeast Corridor riders is that for the first time, Amtrak will start allowing pets on weekend Acela trains later this month.

According to Amtrak, more than 2,700 pets have traveled with their human companions along the Northeast Corridor since October 2015. The railroad began allowing pets on some trains after some animal-loving members of Congress passed legislation last year requiring it.

The fine print: the pet in question must be a cat or dog weighing less than 20 pounds and must remain in a carrier. Advance registration is required and the human must pay a $25 surcharge each way.

For more information, visit Amtrak's pets on trains website.