A new electric Amtrak locomotive. (Rich Pedroncelli/Associated Press)

Amtrak brought 4G service to its Acela trains and a few other routes this year. Now, the rail agency says faster Internet is expanding to other lines and trains.

The Acela trains running between Washington and Boston were the first in this region to see the upgrade. Amtrak made 4G available (emphasis on available — more on that in a moment) on all Acela trains over the last few months, while also adding them on a few lines in California.

All trains that have Amtrak’s WiFi, which includes Northeast Regional trains, will be upgraded to 4G by the end of the summer, Amtrak announced in a news release Thursday.

“We continue to place a strong focus on improving customer satisfaction, and this upgrade is delivering the improved speeds and connectivity required to maintain a competitive edge,” Deborah Stone-Wulf, head of Amtrak’s sales distribution and customer service, said in a statement.

Amtrak first added WiFi to its trains in 2010. The agency says this service, known as AmtrakConnect, can support between 30 and 50 percent of the riders on a train.

Of course, upgrading the hardware and software is not the same thing as promising 4G for the duration of your journey. Riders can access 4G if they’re in an area where 4G is available, but that can vary from location to location. In addition, Amtrak restricts certain things that require lots of data (which means streaming music or videos).

As a result, we’ll probably never be done with tweets like these: